How to tell if frame is bent?

[Morrow]

Just wondering best way to tell if the frame is bent.  Cross member on my 85 k10 i just picked up is mangled, my buddy went hard off roading it and said when he was driving it home one side was offset alot from the other looking at it from the rear.  Could this just be suspension parts?  I looked at the frame and my friends dad looked at it on a hoist and we couldnt see and bends, warps, cracks or major rust damage.  Is the best way just eyeballing it or is there a proper method or test i can do to see if it actually is.  Planning on rebuilding it, so driving it wont be possible, and as there are already some suspension parts mangled, it probably wouldnt be the best way to tell.  Any ideas?

[VileZambonie]

Tram gauge and a few simple measurements will reveal a damaged frame. Is the body sitting abnormal or is it dog tracking?

[red4wd]

Tram gauge and a few simple measurements will reveal a damaged frame. Is the body sitting abnormal or is it dog tracking?

If you are not lucky enough to have a tram gauge you can use a tape measure with plumb lines from points on the frame.  You would need to get an X measurement.  i.e. you would need to measure from left front to right rear, and right front to left rear from the same points on the frame.  The measurement should be the same both ways. 

[Blazin]

You need a level floor. Use the forementioned plumb bob and pick 8 points that are the identical left and right rails. Drop the plumb bob down from then and mark the spot on the floor. Then measure as said before from one corner to the other. Like squaring a foundation before you poor concrete or floor / wall before you nail it together.