I'm going to step out on a limb here and say that anyone who has the old Hemi 4-speed will see the 6-speed as a vast improvement. I don't know what you would use to replace the Viper 6-speed. I know that it will hold up to alot of horsepower, in excess of 1000 hp. So out of interest, what manual trans that we have today would be a better choice. Does Dodge have a better trans out there? Don't all the car co. use trans made by known co. with the bellhousing bolt pattern set up for said engine. Is the viper trans a tremec? I'm not really up to date on the Viper drivetrain.