305.

[pontiac guy]

Why not just rebuild what you have? As was pointed out just about any used trans should be opened up and gone thru. You are talking about transmissions that are 30 years old typically. The 350 was replaced but the OD's which were replaced by the electronic overdrives.

 

[Clone TIE Pilot]

Yeah, that is a very good point about length. And 4R crossmembers- TB, MC, and Cutlass generally used different crossmember part numbers. What those exact differences were, I'm not sure.

But if you get a TH350 for an A-body, I think they're the shorties (6"). So if it's a 6", you're golden. They also have 9" and 12" tailshafts. You want the length to just about match the 200's length. On the El Caminos- did they use a different length tail shaft? They seem to have strange driveline dimensions from what I'm used to. I dunno.

According to parts info, for the 200-4R, if you have an Olds V8 in front of it from the factory, Y or 9, it used trans support p/n 14068895 from 84-88 in any G-body. That means every single V8 Cutlass from 84-88 (and 83 H/O) uses the same 200-4R trans support. Obviously you need to have the frame extension installed if your putting it in a 78-83 Non-H/O frame. Pontiac also used the same support behind the 305 w/200-4R in 84-87 GPs for whatever reason.

The TB crossmembers use rubber blocks where they mount to the frame and off center trans mounts. MC crossmembers bolt directly to the frame without rubber blocks and use on center trans mounts. I don't know what the arrangement is with Olds crossmembers.

The old TH200 crossmember in my Regal had the rubber mounts and offset trans mount. When I did the 231 to 305/2004R swap, the MCSS crossmember didn't have provisions for rubber mounts and used a on center trans mount.

 

[69hurstolds]

The TB crossmembers use rubber blocks where they mount to the frame and off center trans mounts. MC crossmembers bolt directly to the frame without rubber blocks and use on center trans mounts. I don't know what the arrangement is with Olds crossmembers.

The old TH200 crossmember in my Regal had the rubber mounts and offset trans mount. When I did the 231 to 305/2004R swap, the MCSS crossmember didn't have provisions for rubber mounts and used a on center trans mount.

Some Olds G-bodies used rubber isolators on the frame/trans support. Some do not. VIN 9 does not. I don't know the requirements for which cars got isolators or not. I have had only one non-VIN 9 G47 in my life, an 87 Salon with a 4R, and I don't think I was under there except to do an oil change and put on a VIN 9 exhaust system on it. Not sure what it had for support mounts. I don't recall. I would guess that if it were a V8 Olds, they all used the same part number support, thus I can't see a reason they would use isolators for any 307/200-4R combination. I cannot speak with any authority, however. This is just a logical extrapolation.