The first few pictures looked pretty crazy but after seeing the last ones. Am I correct in seeing it's the pump locating the Ultrabell and not the old case where it was cut?

I had a 518 swapped into my 87 Ram. I also moved the crossmember back but used a 92-93 crossmember with a 3 bolt transmission mount.

I didn't really see much change in the mileage. The overdrive just allowed me to drive faster. Same when I lost the overdrive. I went back to driving slower on the highway and with the slower speeds, mileage didn't drop much if any at all.