[Captainfab]

I have no idea how your 496 is built but just assuming it is going to likely put out close to 500 ftlbs, I doubt that 3 speed will last very long. Of course that is subjective to what you will be running for rear tires. If you are just running some skinny street tires that will just go up in smoke, that will be easier on the drivetrain than a set of wide/sticky drag radials.

With that said, for a manual trans, a SM 420 or SM465 should hold up, but won't be any fun shifting. A TKO600 5 speed should hold up and be fun to shift but at a price. For an auto trans a well built TH400 will do the job as well as a 4L80E. Of course the 4L80E will need a controller which adds to the cost.