I know a little about the Tremec 6 spd since one passed thru my hands 10 yrs ago. I sold it for $750 on ebay. DHL shipped it to me after losing the auto tranny I was awaiting. They wouldn't take it back, so I told them I would sell it and they said fine. The input splines vary between Viper and GM models. The Viper version has better internals. There are different factory bell-housings to mount to various engines, plus after-market ones. The shifter is on the top rear, a hole in a rod. I used a socket extension in the hole to shift it and check all the gears. I didn't have my A's and wasn't doing hobby car stuff then, so didn't really consider using it.
