I sized it so the frame rails sit on the top of the 2x6 that runs across the car.
here are some pics.
very crude but works awesome.
I just rolled it out into the driveway tonight for some sandblasting before I replace the rear frame rails.
Yes, I know thats not a mopar on the dolly, forgive me, its a 68 mustang fastback.
however, its sitting between a 74 cuda and a 71 cuda.
just taking time out to build what my youngest son wants.