so maybe this is a dumb question, but I'm still not quite sure what you mean about the difference between the 2 families. Are the cast iron blocks different externally from the alloy blocks? (I assume you meant that there are both cast as well as alloy 117 and 116 blocks)

also, do you happen to know which Tremec box would be suitable, or have any more info about this? Obviously that would be the cheapest route, since those transmissions are pretty common in the States. Thanks for the help

__________________
1999 C43 AMG ~~~ 744 on black, mostly stock
1991 190e 2.6 ~~~ m117 5.6 project car