OK I have already written this once but it got eaten the day the posts dissapeared. So I will try to rewrite it.
It would be best to have a shop measure your truck for you. I have never checked to see if the computerized meauring system we have at work has our rigs on them, but I will check to see if they go back that far on Monday when I go to work. I have the computer hooked up to a car at work now.
To try to do it yourself, Find points along the frame that are in the same place on the left and right rails. Measure from the left front to the right rear points. Then measure from the right front to left rear points. The measurements should be close to equal, w/ in 1/4 in.
A frame that has a "diamond" is easy to get, and easy to repair. You can get a diamond from hitting 1 rail in something. Basicly it will push 1 rail back. You can also get it from pulling on someone from 1 rail. you will then pull 1 rail back. I have done this. I was snatching bushes out of a friends yard, The more beer we drank the bigger the bushes got, and turned into small trees. The last one I pulled was a real challenge, and I was ready to give up on it, and my buddies kept egging me on. I had about 100 feet of strap looped around this MASSIVE bush (that he later told me it had been there as long as he can remember, and he grew up in the house. He was 30!) I kept backing up and hitting it harder, till I backed up to the bush and hit it wide open. I had a cooler in the far back of my Cherokee by the gate that landed in the front seat when I hit the end of the strap. The bush finally came out. It left a hole in the ground about 3-4 feet round and 2 feet deep.
The bush was so heavy I dug up his yard turning the tires over just dragging it to the fire pit. I never seen the bush up close until it was in the pit, the trunk was 6" or better in diameter. Thats what I get for staying in the truck and letting someone else hook me up.
But anyway, I managed to put a diamond in my frame and it would then drive down the road crooked till I fixed it. But you now get the idea of how it can happen from pulling. That and I get a kick outta telling that story.
OK on to measuring...I have looked under my Blazer, and there is no good points to measure from. The best I could find was the flange of the body mount and the flange of the rear spring hanger.
Now you will notice that the trans X-member is in the way to make a straight shot. It is best to use a "tram bar" which is basicly 2 pointers on a bar that can reach around obstructions. Or just find 2 points that are beyond the obstructions. In my case my mufflers hang about 1 1/2 inches below, so I still dont have a straight shot on mine.
It is best to try to make the X about close to even, or longer if possible. The shorter the X is the less accurate it is.
This is really one of those things that I do frequently but have a hard time explaining how to do it. All I can say is to try to find the best points you can to try to measure it from.
If I have confused you, shoot me a P/M.
If ya can't stop.......Smile as you go under!
PIC of mine from flblazers site<a target="_blank" href=http://www.flblazer.alloffroad.com/photo3.html>
GO</a>
