I'll try and explain how I built it, and why I did certain things. I wanted to have it 
so when its dissasembled, it can be stacked up along the wall without any protruding 
90 degree angles. I wanted to be able to unbolt every thing, yet be able to lock it 
all together. 

All the bolts are torqued at 25 ft lbs. There are four little pieces of angle iron, 
one on each corner, and they're welded to the outside rail, then hiltied to the 
floor, so when I bring it in, its always in the same spot, (you don't have to worry 
about an uneven garage floor). And don't worry about putting hilti's into your garage 
floor, I have them for the paint room doors, and three different places for three 
different air compressors, you won't even notice them in the floor.

Move your car or body into the garage, get it in position where you can work around 
it. We'll build our rectangle around it.

Okay, lay out your outside rectangle, c clamp the four corners, weld your little 
pieces of angle iron on the long pieces on the side at both ends.

Check your rectangle with a square and measure diagonally to the four corners, doesn't 
have to be perfect.

Drill the four hilti holes, and tighten it to the floor.

Lay out your corner braces and weld and bolt them in, remember you want access to the 
bolts and nuts that lock it into place. Don't get in a hurry and weld your outside 
pieces to each other.

Now find four points under the car on the frame, mark these points on the frame, 
we're going to stay with the whole car instead of referencing car or body. Plumb bob 
down from the points on the frame to the garage floor, and mark these really good or 
you'll lose them. Use the farthest point out on the frame you can, keep those points 
spread out.

Now go under the car and find the center of the body mount on each side of the car, 
you can start any where you want to. Plumb bob down to the garage floor, mark it 
really good, for both mounts, side to side, like the two just in front of the back 

Get a rough measurement of the distance from the bottom of the body to the floor, 
then get two pieces of threaded rod and the long nut that will give you a little 
leeway on the length. Screw the threaded rod into the long nut, get your post level, 
and just keep the threaded rod level while you screw it back and forth, your're 
measuring right on top of your plumb bobbed mark. You will have to go over a little 
bit, because your rubber body mount is in the way. You can nail the height down 
really close, now gently pull the threaded rod out and take your tape measure and 
write down the length.

Make up your uprights like I made, up in the body jig section, or whatever way you
decide, but keep the washer level at the top of the upright.

Cut your 2" x 2" tubing for the height we just established. I only used six points 
to hold the body, because it was locked in so tight, I didn't use any more.

Repeat this for all 6 uprights, or 8 of them if you want to.

Get the car out of there, you can unbolt the front bar or use floor jacks to get 
it over it.

Get a cross bar and lay it on the long pieces, we'll do the two mounts in front of 
the back wheels.

I did this alone, but two people will make it easier, your going to c clamp the 
uprights to the cross bar and manuever the uprights directly on top of your plumb 
bob mark on the garage floor, tape your post level to the uprights, you might have 
to put a weight on the cross bar to keep it from moving around, once you have the 
two uprights centered and leveled and c clamped to the cross bar, mark or spot weld 
two little short pieces on each side of the cross bar, the cross bar will be bolted 
to those two little pieces.

Now spot weld the upright to the cross bar, then do the other four or six.

Keep the post level on the upright as you weld it solid to the cross bar, get a 
helper to keep it level with the post level so you don't pull it, it will pull a 
little but, you will be okay.

After I had every thing welded up, I took the body off the frame and I was wondering 
how it would all line up, if you make one of these jigs, you'll know the feeling.

Anyway the body set down with a couple little gaps because it will spring a little 
when you unbolt it from the frame, but I bolted mine right on, no adjustments, and 
you will see with just 6 uprights, its like a rock, nothing moves.

There are probably easier ways to do this, but this way works, I hope I explained 
it half way decent, just think it through as you go, make sure I didn't lead anybody 
astray with any of this.