How to check for bent Lower A-arms?

Any ideas how to check 1 piece Rocket lowers to tell if they are bent? We picked up a few of them at a swap meet, plus I have a few of our own that we replaced after some 'contact'. Just by looking at them, they appear to be ok, no weld cracks or paint cracks as far as I can tell.

Measure a known good lower and then measure the others. The measurements should be pretty close. I would be suspect of anything 1 inch short but I have seen some new measure almost that far out when a change was made in the manufacturing for adjustability.