Here's how I have dropped the gearbox first. Probably a method used more for when one is pulling the gearbox to work on it. But if you want to separate the gearbox from the motor before pulling the motor, here's one of many different ways. You can see the end of the torque tube shaft up against the bottom of the floor, which gives lots of room to slide the gearbox backwards in order to drop it. I lower it to the ground and slide the gearbox out from under. I'm sure there are tons of different ways to pull the gearbox first, such as using a floorjack, etc and sure others will chime in with their ideas.
Craig
My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear My truck ....... Respect The Rust If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.
