This is the idea I've been working on for a tummy tuck cross member. I bought some cross member mounts from Ruffstuff Specialties and some 2"x2"x1/4" square tubing. Plan is to weld the mounts to the inside of the frame and run the square tubing in between the mounts. As far as the actual tranny mount I unbolted the rubber mount from the bracket and cut the studs off. I'm going to weld the mounting bracket to the square tubing. link to the mounts below.