trans mount for 0500 swap
You have to build your own. Use the search function and you'll find numerous threads about an OD swap. some have pics.
From what I've read, the trans mount is the least of the problems in installing either of these overdrive transmisions into an A Body.
The overdrive unit is located inside the tailshaft housing, and is large enough in diameter, that it won't fit without a considerable amount of floorboard surgery. I don't think there's a problem otherwise; just the tailshaft housing being too big to fit.
To be sure, building a new crossmember/transmission mount is a job to be reckoned with, but IMHO, the floorboard surgery would be more difficult, and patching it up, afterwards.
I have a 518 in my '93 Dakota 318, and would love to have one in my '72 Valiant, but I don't think I'm up to it... :angry2:
Good luck!!!