transmission

Hello;
I'm restoring a 1971 GTO.
The transmission seems ok, but since I'm replacing the V8 400 engine (old and beaten down) to a 455 ci. I'm wondering if it's best to get a new muncie or is the old muncie good enough to support the new engine?

thanks for the comments and suggestions!

I would suggest that if the trans is quiet and shifts well, just change the lube in it, although it wouldn't hurt to open it up and look for shaft wear, worn bearings, chipped teeth, worn synchros and pretty pieces of metal or filings in the bottom of the case.
Better to do it now while its easy to get to.

Any standard trans that was stock in a GTO will handle a 455. It the trans original?

The big 4 speed Muncie's (M-21 and M-22, I think) are very strong and will easily cope with a 455.
You did not say if you had a 4 spd or a 3 spd standard. I never heard of anyone complaining about a 3 speed Muncie, although the 3 speed Saginaws and the Muncie M-20's are weak. Check here to see what you have
http://www.gtoalley.com/transns.html

Thanks for the info, I'll do just that.
The muncie is indeed a four speed, theres some noise but I been told by AAMCO that these transmissions weren't equiped with some sort of isolation chamber that would minimized noise.
I will check out another transmission place as well to get a second opinion, and yes the tranny is the original one.

Thanks again for the info.

I'm almost sure I'll ask you again a few more questions, this restoring thing is a lot work!