[blykins]

I see no benefit in running a T-56. It will be hard on your wallet, not only for the price of the trans, but for the driveshaft and everything else that you will have to buy for it. If you run a twin disc, the midplate will need to be modified for an adjustable ballstud plus you'll have to run a notched fork. Otherwise, it will be hydraulic throw out bearing.

I'm a T-56 hater, plain and simple. Too long, too big around, too heavy, not enough benefit from another gear to spend that much money.

You would not be able to tell any difference in performance between a 3.73 and a 4.10 gear. My $.02 would be to run the TKO 600 you have, put a 3.73 in the rear, and cruise at 70 in the lower 2000's.