I made mine. a plate with a pipe welded to it bolted to the bench. then I torched out a big C shape. welded another tube to fit inside the bench piece. then welded the acme thread and the "nut" part from a 6" C-clamp to both ends of the C. Built a few dozen GM units with that fixture. It's bolted to my buddies bench right now or I'd post a few pic's. He is building a 4L80E for his truck. Keith
Here is a pic I found that shows an easy one to build