How does the viperspec transmission differ from the LS1/LT1 transmissions pictured above? (If at all)

 

A viper "spec" trans is just a standard transmission (LT1, LS1, etc.) with a viper mainshaft. (shortened and tailhousing machined larger)

A real viper spec has a longer tailhousing, and it's slave cylinder bolt holes are clocked differently than the LS1 Fbody.


Slave bolt holes at 2 and 8 o'clock

 

Besides the tailshaft, what is different externally between the vette and gto/f-body ones?
Mounting holes for the slave cylinder? Thanks

 

The vette front plate has no provisions for a slave, it mounts to the torque-tube and remote shifter linkage.. It can't bolt behind an engine without changing the front plate, adding rear shifter linkage, and tailhousing/mainshaft/etc..