Loader adapters are where a Cat J-series quotation goes wrong. The tooth carries the rung — J300 on a 950, J350 on a 966, J400 on a 980 — and buyers stop reading there, because the letter is the only part of the number that looks like a specification. The base underneath is a separate casting with a separate number, and on the loader ladder the same rung is offered with at least five different ways of attaching it to the lip. Two of those ways are bolt-on, and those are the two this page covers in full: the top bolt-on family, the side-pin family with one or two holes per side, and the bolt-and-nut pair that goes with every casting in both.
1. What the catalogue means by "bolt-on"
The loader adapter tables print a mounting method beside each casting, and the method is literal. A top bolt-on base is fastened down through the casting into the bucket lip; the bolt pattern has to exist on the lip already, and the base can be unbolted in a yard. A side base is fastened through the side of the casting instead, and the tables then split it by how many holes there are per side — the catalogue headings read Bolt-On Side 1 Hole and Bolt-On Side 2 Holes. Nothing in the tooth number tells you which of the three you are standing in front of.
The weld-on families are the other half of the adapter landscape — flush weld-on, bottom strap weld-on and weld-on heavy duty — and we cover those separately in the loader teeth and base guide for the 950, 966 and 980 class. What follows is only the bolted side of the ladder, because a bolted base is the repair a customer can plan and the one most often mis-quoted.
2. Top bolt-on bases, J200 to J450
Eight castings cover the bolted-from-the-top option across the loader ladder. Weights and A × B × C sizes are the ones printed in the TRASTEEL TSJ loader adapter tables:
| Rung | Adapter | Weight | A × B × C | Machine lines as printed | Bolt / nut |
|---|---|---|---|---|---|
| J200 | 9J-4207 | 3 kg | 262 × 89 × 20 mm | 910 / 914 / 931 / 933 / IT12 | 5J-4771 / 2J-3506 |
| J250 | 1U-0257 | 8.9 kg | 340 × 124 × 25 mm | 916 / 920 / 924 / 926 / 928 / 930 / 936 | 8J-2928 / 8J-2933 |
| J300 | 4T-4307 | 13.2 kg | 405 × 160 × 32 mm | 950 / 955 / 960 / 963 | 8J-2928 / 8J-2933 |
| J300 | 3G-9307 | 14.7 kg | 405 × 165 × 32 mm | 966 | 5P-8361 / 5P-8362 |
| J350 | 3G-3357 | 16.9 kg | 418 × 150 × 38 mm | 960 / 966 / 970 / 973 / 977 / 972G | 5P-8361 / 5P-8362 |
| J350 | 1U-1357 | 19.8 kg | 430 × 156 × 45 mm | 980 / 983 | 5P-8361 / 5P-8362 |
| J400 | 6I-9898 | 27.5 kg | 460 × 156 × 45 mm | 977 / 983 / 980 | 5P-8361 / 5P-8362 |
| J450 | 8E-2467 | 25.5 kg | 455 × 156 × 45 mm | 980 / 988 | 5P-8361 / 5P-8362 |
Two things stand out. The bolt pattern changes three times going up the ladder: the J200 casting takes 5J-4771 bolts with 2J-3506 nuts, the two lightest mid-size rows take an 8J-2928 / 8J-2933 pair, and everything from 3G-9307 upward is held by 5P-8361 bolts with 5P-8362 nuts. And the rung overlaps: 4T-4307 and 3G-9307 are both listed as J300, 5 mm apart in width and 1.5 kg apart in weight, but they are printed for different machines — 4T-4307 for the 950 / 955 / 960 / 963 class, 3G-9307 for the 966. A bare "J300 base" quote is a coin toss between two castings.
3. Side-pin bases: one hole per side
Where the lip has no top bolt access, the catalogue offers the side family. Five castings cover one hole per side, from the compact rung to the 966:
| Rung | Adapter | Weight | A × B × C | Machine lines as printed | Bolt / nut |
|---|---|---|---|---|---|
| J200 | 1U-2208 / 1U-2209 | 4.1 kg | 122 × 76 × 20 mm | 910 / 914 / IT12 | 6F-0196 / 2J-3505 |
| J250 | 3G-4258 / 3G-4259 | 10.4 kg | 133 × 105 × 25 mm | 916 / 920 / 924 / 926 / 928 / 936 | 4J-9058 / 8J-2933 |
| J300 | 3G-4308 / 3G-4309 | 15.5 kg | 175 × 120 × 25–32 mm | 950 / 955 / 960 / 963 | 5P-8823 / 5P-8362 |
| J300 | 3G-8308 / 3G-8309 | 16.5 kg | 198 × 140 × 32 mm | 950 / 955 / 960 / 963 | 5P-8823 / 5P-8362 |
| J350 | 3G-5358 / 3G-5359 | 20.4 kg | 213 × 140 × 32–35 mm | 960 / 966 / 973 / 977 | 5P-8823 / 5P-8362 |
The one-hole family is printed as number pairs, and 3G-4308 and 3G-8308 show why the strap matters more than the rung. Both are J300, both are printed against the same 950-to-963 machine list, and they are 1 kg apart — but the strap jumps from 120 mm to 140 mm across the pair, and the casting grows from 175 mm to 198 mm long to carry it. If the width across the pocket is what you measured off the bucket, that is the number that decides between them.
4. Side-pin bases: two holes per side
Four castings, and this is the family that separates the plain models from the F-series:
| Rung | Adapter | Weight | A × B × C | Machine lines as printed | Bolt / nut |
|---|---|---|---|---|---|
| J250 | 6I-9250 / 6I-9251 | 12.7 kg | 190 × 168 × 25 mm | 916 / 920 / 924 / 926 / 928 / 936 | 4F-4042 / 2J-3507 |
| J300 | 8E-5308 / 8E-5309 | 18.4 kg | 200 × 163 × 25–32 mm | 950G / 960F / 962G | 8T-9079 / 3K-9770 |
| J350 | 8E-5358 / 8E-5359 | 26.3 kg | 245 × 180 × 32–35 mm | 960F / 966F / 970F / 972G / 973 | 6V-6535 / 3K-9770 |
| J400 | 6I-8243 / 6I-8244 | 35.1 kg | 273 × 207 × 45 mm | 980 / 982 | 5P-8361 / 3K-9770 |
This is the family where a one-character difference costs real money. 3G-5358 is the J350 one-hole side base at 20.4 kg, printed for 960 / 966 / 973 / 977. 8E-5358 is the two-hole side base at 26.3 kg, printed for 960F / 966F / 970F / 972G / 973. Same machine family, same rung, two different bolt counts, and 5.9 kg of casting between them. The F-prefixed machines appear on the two-hole rows — 8E-5308 carries 950G, 960F and 962G, none of which turn up on the one-hole rows — so on an F-series rebuild the heavier two-hole casting is the one that is printed against the machine.
5. The bolt is not the nut
Fasteners are where a rebuild quietly stops fitting. Across the bolted loader adapters the same bolt number appears with two different nut numbers, so a quotation that lists bolts only is incomplete:
| Bolt | Nut as printed | Adapter rows | Mounting |
|---|---|---|---|
| 5J-4771 | 2J-3506 | 9J-4207 (J200) | Top bolt-on |
| 8J-2928 | 8J-2933 | 1U-0257 (J250), 4T-4307 (J300) | Top bolt-on |
| 5P-8361 | 5P-8362 | 3G-9307 (J300), 3G-3357 (J350), 1U-1357 (J350), 6I-9898 (J400), 8E-2467 (J450) | Top bolt-on |
| 5P-8361 | 3K-9770 | 6I-8243 (J400) | Side, two holes |
| 5P-8823 | 5P-8362 | 3G-4308 (J300), 3G-8308 (J300), 3G-5358 (J350) | Side, one hole |
| 6F-0196 | 2J-3505 | 1U-2208 (J200) | Side, one hole |
| 4J-9058 | 8J-2933 | 3G-4258 (J250) | Side, one hole |
| 4F-4042 | 2J-3507 | 6I-9250 (J250) | Side, two holes |
| 8T-9079 | 3K-9770 | 8E-5308 (J300) | Side, two holes |
| 6V-6535 | 3K-9770 | 8E-5358 (J350) | Side, two holes |
Read the two 5P-8361 rows together and the trap is visible: the same bolt is published with nut 5P-8362 on the five top bolt-on castings and with nut 3K-9770 on the side two-hole casting 6I-8243. Nut 3K-9770 also ends the two heaviest side two-hole rows, 8E-5308 and 8E-5358, which are held by completely different bolts — 8T-9079 and 6V-6535. Meanwhile the compact end of the ladder stays in its own series: 2J-3506, 2J-3505, 2J-3507 and 8J-2933 appear nowhere else on the bolted adapters. We quote bolts, nuts and washers against the casting number rather than selling "J350 hardware", because on a 20-point lip the difference between the right nut and a near one is a loose base and a damaged pin bore.
6. What a heavier base really costs
Weights are published per casting, so the cost of the adapter decision can be worked out before the order is placed. Here is the J350 line across its mounting families, and the J400 line for comparison:
| Mounting | J350 (960 / 966 class) | J400 (980 class) | Fastener |
|---|---|---|---|
| Top bolt-on | 3G-3357 — 16.9 kg (1U-1357 19.8 kg) | 6I-9898 — 27.5 kg | Bolts down through the casting |
| Side, one hole | 3G-5358 — 20.4 kg | — | Bolts through the side |
| Side, two holes | 8E-5358 — 26.3 kg | 6I-8243 — 35.1 kg | Bolts through the side |
| Flush weld-on | 1U-1354 — 13.2 kg | 107-3404 — 19.6 kg | None — welded to the lip |
| Bottom strap weld-on | 1U-1350 / 1351 / 1352 — 9.5 / 10.2 / 10.2 kg | — | None — welded to the lip |
| Weld-on heavy duty | 135-9354 / 9355 / 9356 — 14.4 / 14.5 / 14.5 kg | 125-8404 / 8405 / 8406 — 18.7 / 19.7 / 19.7 kg | None — welded to the lip |
On the J350 line the castings run from 9.5 kg for the bottom strap weld-on to 26.3 kg for the two-hole side base — a 16.8 kg spread on the same bucket. Between the two castings a customer is most likely to mix up, the top bolt-on 3G-3357 and the two-hole side base 8E-5358, the gap is 9.4 kg per point: 112.8 kg across a 12-point lip, 225.6 kg across 24 points and 376 kg across 40. That weight appears on the freight invoice for every set, and it is paid again each time a base is replaced — which is how a 55% heavier casting turns into more than arithmetic. On the J400 line the same comparison runs 27.5 kg (6I-9898) against 35.1 kg (6I-8243), 7.6 kg per point and 182.4 kg across a 24-point lip.
The heavier casting is not a mistake. A two-hole side base carries more metal around the pocket and more bolt area where the nose takes its load, and on a face-loading loader that is exactly what a customer is buying. The mistake is ordering it when the lip is drilled for one hole and the bucket rehandles gravel, or ordering the lighter casting onto a face that will pull it. Mounting first, weight second.
7. What to photograph before you order
- The lip, from above — bolt heads visible in a row means a top bolt-on base; bolt heads on the side face mean a side base.
- The side of one base, square on — one hole or two. This single photograph settles 3G-5358 against 8E-5358.
- One worn casting, in your hand, if any number is still legible — the number beats every measurement.
- A tape across the pocket and along the strap, plus the pin bore if the base is being replaced because the pin was moving.
- The machine plate — 966H, 966F, 980G. The F and G suffixes change which casting the catalogue prints against the machine.
We supply the loader side of the J-series as aftermarket castings — teeth, adapters, pins, retainers and hardware quoted on one line, matched to the numbers printed above and shipped FOB Shanghai or CIF. Nothing on this page is a genuine Caterpillar part; the numbers are used to cross-reference fitment only. For the rung-by-rung picture behind these bases, start with the 950, 966 and 980 loader teeth and base guide, the full J-series ladder from J200 to J800, or the bucket teeth and adapters catalogue page.
FAQ
Q: What is the difference between a top bolt-on and a side bolt-on loader bucket adapter?
A: Where the bolts pass. A top bolt-on base such as 3G-3357 (16.9 kg, 418 × 150 × 38 mm) is fastened down through the casting into the lip on bolt 5P-8361 and nut 5P-8362. A side base such as 3G-5358 (20.4 kg, 213 × 140 × 32–35 mm) is fastened through the side of the casting on bolt 5P-8823 and nut 5P-8362, and the catalogue splits that family by holes per side — one hole (3G-5358, 3G-4308, 3G-8308) or two (8E-5358, 8E-5308, 6I-8243). The two are not interchangeable on the same lip.
Q: Which adapter does a Cat 966 take — 3G-3357 or 8E-5358?
A: Both are printed for the 966 line and they are 9.4 kg apart. 3G-3357 (16.9 kg) is the top bolt-on casting, printed for 960 / 966 / 970 / 973 / 977 / 972G; 3G-5358 (20.4 kg) is the one-hole side base, printed for 960 / 966 / 973 / 977; 8E-5358 (26.3 kg) is the two-hole side base, printed for 960F / 966F / 970F / 972G / 973. The badge does not decide — the bolt pattern on the lip does.
Q: Do the bolts and nuts stay the same across the loader adapters?
A: No. Bolt 5P-8361 is published with nut 5P-8362 on all five top bolt-on rows but with nut 3K-9770 on the side two-hole casting 6I-8243, and nut 3K-9770 also sits behind the 8T-9079 and 6V-6535 bolts on the two heaviest side rows. The J200 castings use their own series entirely (5J-4771 / 2J-3506, 6F-0196 / 2J-3505). Order bolt and nut as a matched pair against the casting number.
Q: How do I confirm the base number if the casting has worn smooth?
A: Measure and count instead of reading. Count the bolt holes per side, measure the strap width and the pocket, then send the machine plate and the lip photograph. On a 966 that combination leaves a short list: 418 × 150 × 38 mm with a top bolt pattern is 3G-3357; 213 × 140 mm with one side hole is 3G-5358; 245 × 180 mm with two side holes is 8E-5358. We confirm against the printed tables before quoting.
Sources
Adapter numbers, published weights, printed A × B × C dimensions, the machine lines and the bolt and nut pairs on this page are taken from the loader adapter tables of the COHIDREX TRASTEEL TSJ catalogue (metric), read against the same source used for the loader teeth pages on this site. Where a number is published with different weights in different catalogues we print neither figure as fact — we weigh the casting before it ships. TRASTEEL and the J-series are third-party aftermarket systems: Caterpillar and the part numbers referenced are the property of their respective owners and are used here to cross-reference fitment only.