Transmission help

So here's my little story. My first car was/is a 1976 Buick Regal. I still have the car, with 89,000 original miles. You can see the pictures of it I took 2 years ago below. The car has sat all of the past 3 years because my transmission went poo (all reverse and no forward). Good news is, it's been garaged all those years.

I have decoded the VIN to tell me that the O.E. engine is a 350, but I was mislead to believe for years that my car had the Chevy 350 and not the buick 350. I didn't know the difference in the transmissions at the time, and found a great deal on a TH400 completely rebuilt and bought it. Today, I towed the car out of my garage to a mechanic friend's place, only to have him tell me that I have the Buick 350, and a Chevy TH400 transmission.

My question is this. I know the TH350 is shorter than the 400, but I can't find anything comparing the 400 to the Buick transmission. Will a bellhousing adapter up to the 400 fit in my car with the standard driveshaft?

Why don't you have your original transmission rebuilt? It's the right one for the car. If you get a used one that's not exactly right or has the wrong converter the car won't drive good. The wrong transmission will be a headache to install or you may have to do it over. That is a Buick engine.

I priced out a transmission rebuild and it would have ran about $1200. I bought the TH400 completely rebuilt with a shiftkit for $400. My friend and I can swap them. That's why I started down this path.

T

Can you get your money back on the Chevy trans? By the time you get it adapted to the Buick engine you will have spent as much as having the Buick trans rebuilt. A bargain is not always a bargain.

GM built two versions of the TH and 200 R4 trans'. One with the Chevy bolt pattern and one with the BOP (Buick, Olds, Pontiac & Cad) bolt pattern. Aftermarket manufacturers make an adapter to put the BOP trans on the Chevy engine but do not make an adapter to put a Chevy trans on a BOPC engine. Of the bellhousing of both patterns only the lower two bolt holes and the locating pin holes right above them are common to all the engines. The four bolt holes above the locating pin holes on the Chevy trans will not line up with the the holes in your engine block.

So, either get your trans rebuilt or look for a good or rebuilt Buick trans (has starter on passenger side, Pontiac has starter on driver side).

The trans will fit the Buick believe it or not. Only 4 bolts are in the same place but it will hold.

First, if your distributor is in the front, it's a Buick motor.

Second, Buick and Chevy bellhousings are different. Only the dowel pins and TWO bolts are common. You can buy adapter plates from the aftermarket.

Third, the TH400 is longer than your TH350. The trans crossmember moves, the driveshaft needs to be shortened, and the front yoke on the driveshaft is different. The TH400 was factory installed behind the 455 in your car, but you would need to find those parts.

Fourth, the TH350 is about the least expensive GM trans out there. Perfoemance rebuilds are available in the $600 range.

I'm sorry, but while the TH400 swap is certainly possible, you questions tell me that you do not have the experience to do it. If you are paying someone to do it, you will spend more than the cost of rebuilding your original trans, or getting a correct rebuilt TH350. That is your best option.

Thanks everyone. I guess my question was more ofWhat is the BOP transmission and length. You are all correct in thinking that I am a newbie. I want to learn about maintaining the car, because it is a fun past time of mine (when I get to help people who know what they're doing), but unfortunately no one can take the time to teach me and I will end up wasting a lot of time and money going about it on my own. Hopefully I can get what I paid for the trans back out of it, even though the cost of shipping will be a loss. Thanks for all your help! Back to the drawing boards...

Thanks everyone. I guess my question was more ofWhat is the BOP transmission and length. You are all correct in thinking that I am a newbie. I want to learn about maintaining the car, because it is a fun past time of mine (when I get to help people who know what they're doing), but unfortunately no one can take the time to teach me and I will end up wasting a lot of time and money going about it on my own. Hopefully I can get what I paid for the trans back out of it, even though the cost of shipping will be a loss. Thanks for all your help! Back to the drawing boards...

Your original trans is a BOP TH350. It is considerably shorter than the TH400. Both were factory available in your car, but converting from one to another entails the changes I described above. Chevy transmissions of the same type are the same length, but the bellhousing bolt pattern is different. As I noted, the TH350 is about the most common GM trans ever. Rebuilds in both stock and high performance versions just about grow on trees. I've seen relatively stock rebuilds priced at $450 and up. $800 seems to be the going rate for a mild high-performance version. Be sure to specify the BOP bolt pattern and 6" tailhousing. Of course, these prices are just for the trans and do not include installation.

I agree that you should get the stock trans rebuilt. It may seem like a lot of money but how long do you plan to keep the car? Also adapting a different trans will save nothing even if you get it for free. Look at what they charge for shop time these days, and the hand work and different parts needed for an adaptation.

Writing the check will be painful but a year from now you will be glad you did it right.

The no fuss or muss answer is rebuild what you have. Truth be told, I have seen better luck with rebuilding the original compared to replacing with another rebuild.