ok so one of my co workers has a 77 trans am that originally had a 403 but at some point of the cars life it had a 350 put in it , now he bought a olds 403 motor that came with a auto tranny but he wants to keep it a 4 speed which it is now , but the problem is the bell housing and flywheel do not match to the 403, now my question is what bellhousing from car will work or what other trannys will work on this motor. any suggestions will be helpfull

 

As you have found out Chevy bellhousings and BOP bellhousings are different. There is an adapter plate that you can buy to bolt them together if you want. As far as what transmissions you can use with the 403, the only one I ever used was a TH350. If it had a Chevy 350 in it then you will also have to change the motor mounts if you want to put a 403 back in it.

 

I think lakewood makes a sfi bellhousing that will mount a buick olds pontiac motor to a typical muncie 4 bolt style gearbox. You will need to change motor mounts and flywheel also. Or find an original bop style bell housing but that could be difficult.

 

what company sells the adapter plates?
yea as we found out they had welded on the 350 mounts, but we broke the welds on them and put the stock 403 mounts on only thing holding us back now is the bell housing and the flywheel.

i believe the 4spd in it right now is a borgwarner , not to sure though might be a muncie. would the same adapter plates work for the muncie and the borgwarner?

 

http://www.jegs.com/i/JEGS-Performan...oductId=751074

 

I wouldn't use that adapter for a manual transmission. Get the right part.
http://shop.ebay.com/i.html?_nkw=old...=p3286.c0.m359

There are also a few on car-part.com for $50.

 

why wouldnt the adapter plates be a good idea?

 

There just not the correct way to do things. Even if they work well. I myself would rather have a bell housing for my application if it werent to expensive.

 

It screws with the throwout bearing travel, etc. Adapters are ok for automatics, but not for manuals IMO.

 

And pulls the input shaft out of the pilot bearing a considerable amount which could cause premature failure IMO