How bent is this frame?

[dracko]

Been working on my ‘64 swb fleetside for a while now. Recently had some buddies help install the new repop bed. It lined up good, but noticed quick that the rear drivers side frame rail is bent down about 1/2” lower than the PS rail.

Tonight I bolted up the cross rails that the wood sits on, with new rubber pads under them, and ran a string line across the top of the rails to the rear cross brace that the wood sits on. This brace is not on pads and shouldn’t be based on the LMC diagram.?

I was pretty surprised to see that when just touching the cross braces, the string is about 3/8” high of the rearest brace on the PS and prob 9/16” on the DS.

Wondering if i’m missing something or if it’s all assembled properly and actually is that bent from years of abuse. Thanks in advance for any insight.