Cat D6C 76A1329 - Need a Replacement Engine

The original engine would be a D333A (4-1/2" bore) and similar to the 977 53A. The 69M D333C is from an early 627 scraper (4-3/4" bore). Can't help you on the interchange.

The 76A D6C use the 4.5" bore D333B engine which was used in the 977H, 966B and 14 grader of the same era, only trouble is, the D6C has a flywheel housing and accessory drive different from all the other machines so that will need changing along with the injection pump and turbo etc.
You are really looking for a D333B 'long block'.

Thanks guys! Anyone know of a good place to find a D333B long block? I'm in Columbus Ohio.

I don't believe that is correct.
The 76A uses the D333A engine.
According to my Cat Serial/Product Identification Number Index, the only D333B engines listed are for an 80B Marine engine and a 79B Industrial engine.

If there are other applications I'd like to know.

Other options for the A engine are 59B1-59B989, 87B1-up, 88B1-up Industrial engines.
D5 83H1-up, 84H1-up
D6 74A-74A3108, 76A-76A6061, 82A-82A620, 83A - 83A910
#12 73G1-up, 12E 99E4266-up, #14C 35F1-35F1284, #14D 96F1-up.
966A 33A -33A2110, 966B 75A-up, 57H-up
977H 53A-up 46H1-up

Choices of complete engines will be limited by oil pump and sump arrangements, tractors use the three section oil pump. Bolt on items will vary.

On looking through my old machine index OM, the D333'A' suffix is not used on any of the 1960's 4.5" six cylinder engine machines as the engine carries the same serial number as the machine. The engine to find is one from a genuine D6C even a UK equivalent 82A/83A. Any other engine will mean parts to swap over,( there are at least five different governors fitted) but if you go around dealers asking for a D333A you are likely to finish up with a naturally aspirated engine without the essential piston cooling sprays.
The D333B was a turbocharged marine and industrial engine introduced around 1959, which will need a few changes but it did have piston sprays fitted, hence, on this side of he pond at least, we regard the turbocharged version as the D333B, or should the 'B' only be used for the aftercooled engines?

Yes, the later D333's and the D330's seem to fall in a "black hole" in terms of designation. There does not seem to be any designation for a "B" series although we'd like to think there was something in between the "A" and "C" that covers the many intermediate changes like the D333T and D330T. As an engine exchange it would be best to pick from a known engine application to best match a replacement. I'm thinking you'd get the same blank response when requesting a D333B engine.

I think I would go with th 977 53 A engine ,I have a 76A D-6 ,and the 977 53 A Is the same vintage .You may have to change the bell housing and flywheel as the 977 has a converter behind the flywheel where as the d-6 an oil clutch .
May have to call a cat dealer and check the racksetting differences between the 2 machines ,and add or remove shimes in the rack .

Ok wow you guys know your stuff. I plan to pull the engine this weekend and take it to compare with the 53A I found. Beginning to think maybe I better off having this one rebuilt.

Welcome to ACMOC Beachyw. Good luck with your engine project. If you need a parts book for this tractor, I just posted one in the For Sale/Wanted section.
Thanks,
Craig