Hi im new on here and im looking for a 4 speed , that will take some abuse from a 71 455 w/ 10.5 to 1 comp, 292 dur .520 lift cam, stock nodular crank, stock rods, G heads mildly ported, performer intake, 850 dp holley, 1 7/8" headers, 3" dual flowmasters, in a 1983 Trans Am wieghs about 3300 lbs w/455 & th400 (im still in process of this build any sugestions would be great.)

 

The Muncie trans in its "stock" form is marginal behind a 455 that will be thrashed... There are several companies that make upgrades for the muncie that will handle it...That being said the Muncies are getting expensive and the upgrades add on to that price.. If it were mine I would put a Borg Warner Super T-10 tranny in the car.. The tranny is basically the same overall in size so there is no butchering required, it is stronger right out of the box, they are less expensive to find used and they have many different gear ratios to chose from..... Depending on your rear end ratio you might look at 2.64 first gear model, if you wanted a taller rear end to help mileage and crusing you might look at the 2.88 first gearThey also have 2.52 and all they way up to the 2.20 first gear...

Overall a better tranny, less money and more choices.

 

If you are not into any numbers-matching or originality,then I would have one built,using aftermarket parts.The cost is a little more than your typical rebuilt Muncie,but you will have a much beefier unit.
The other thing you will need to do is make sure your 455 is drilled for a pilot bearing.If the crank is out,you can get it drilled.It just needs to be spot-on. they do make an adapter style bearing that allows you to use an auto crank,but I'd rather use a crank that is drilled.