different oil pans?

Riddler, you're being incorrectly too matter of fact. There's a few options for clutch/flywheels. Depending on the person's use needs and pocketbook:

3/4 ton Hemi Ram flywheel and clutch
Challenger flywheel and dual disc clutch
McCleod has several choices
Fidanza
SPEC

I'm using a SPEC flywheel / dual disc clutch for a Challenger application in my 392 Cuda

I guess your right. But I did do a few searches for info and could only find McLeod being used for swaps. I'm guessing that it because of cost. Might be time to build a webpage with info for swaps. Maybe just a list of the products that work with pictures and part numbers.

Riddler