First make sure your overhead beams(rafters) can safely support the cab.
How would one go about that?
Trusses, by design, support loading from the roofing surface. So all the upright truss memebers are in compression. If you use the lower truss cross timber to try to lift objects in your garage you are effectively putting the upright truss memebers into temsion, which is now trying to pull the truss members apart. Depending on how the members are fastened together this may actually tear the truss members apart.
Have folks done this? Yes. Have I done this? Yes
(For a Jeep hardtop, which is very light.)
The last thing you want is to have to do structural repairs to the roof trusses of your house, when what you really wanted to do was work on your truck.
Using floor jacks or an engine hoist is a much safer and more logical method.
By far the least expensive way is to get (3) folks over to help and simply lift the cab off the frame.
Have fun and be safe out there!
