Squaring up new bed on step side truck

[wideboots]

I have just completed bolting together a new bed (brand new sheet metal from Mar-K) for my 1978 Chevy 1/2 ton step side truck.  Sides, front bed panel and rear cross sill are all bolted together.  The tail gate is not yet installed.  The measurements on the top and bottom of the front bed panel and back of the bed are identical at 50 inches.    However, the measurements from corner to corner are off by a half inch.  Can someone please tell me how I get my new bed square?  This is probably easy, but I can't figure it out.  Please help as soon as possible.  I would like to get the bed on the truck this weekend if possible.  Tell me the trick please

[Blazin]

Might be as good as it gets. Did you leave every bolt loose until the whole thing was assembled? If you tightened bolts before the whole thing was put together it might have thrown something out of whack.

[Captkaos]

The sides are always going to be 50" end to end.  You can't change the length of the bedsides.  You just need to make the corner to corner measurments the same and you are done.

[VileZambonie]

These trucks had the worst body lines ever - eyeball it til it looks good 

[80stepsideguy]

Your best bet is to loosen everthing and add the center braces in to stiffen the entire thing and then retighten it.A 1/2 a inch isnt bad, now if you were off say 1 0r 2 i say yeah theres a problem but your close.Plus remeber your dealing with aftermarket pieces so it isnt always going to be exact...

thanks
pat

[123 pugsy]

You just got to push the two corners of the 1/2" over towards each other with a helper and it should move. Don't push too much.Its only out 1/4".