The Tremec 5008 is the Ford based TKO-600 transmission. The bolt pattern fits the top loader pattern which means the Mopar guys have to modifiy to make it fit. Classic has a cast small block bell housing that supports the LA small block family and the new 3G HEMI engines. Keilser has a big block cast bell housing. Quick Time manufactures a small and big block units for the TKO series of transmission as well as the Viper and GM based T-56 six speeds.
The new TR6060 six speed that is in the new Challengers, Mustangs and Camaros is a very large transmission that will not be a "user freindly" installation into our older E-Bodies. I was told back in November not to expect any of the aftermarket 6060 units available for sale until late in 2009. Not saying you can't get them, but it maybe a long wait.