The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

ray_mcavoy · 02-23-2018, 01:50 AM

I ran into the same issues with rusty cross sills when restoring the wood floor in Dad's '77 GMC.

With the exception of the rear cross sill (back by the tailgate), the 67-72 cross sills can be used as suitable replacements. The plank widths are different so the hole spacing in the cross sills is different. But when I contacted Mar-K, they were able to supply some 67-72 style cross sills without any holes drilled in them. So (using an old one as a template), I was able to drill them out to the 73-80 hole spacing.

For the rear cross sill (and many of the special flange pieces around the perimeter of the floor), we had a local metal fabrication shop make replacements using the old rusty pieces as templates. But I think it would be possible to purchase a 73-87 rear cross sill that's meant for the more common steel floor and modify it to work with the wood floor. That would basically involve cutting out a section across the leading edge, flipping it over, and re-welding it back in to create the recessed notch that the ends of the planks sit down into.

The metal strips that go between the boards are available through Mar-K with the holes pre-punched for the 73-80 wood fleetside beds.

02-23-2018, 01:50 AM	#2
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,354	Re: 73 woodbed help I ran into the same issues with rusty cross sills when restoring the wood floor in Dad's '77 GMC. With the exception of the rear cross sill (back by the tailgate), the 67-72 cross sills can be used as suitable replacements. The plank widths are different so the hole spacing in the cross sills is different. But when I contacted Mar-K, they were able to supply some 67-72 style cross sills without any holes drilled in them. So (using an old one as a template), I was able to drill them out to the 73-80 hole spacing. For the rear cross sill (and many of the special flange pieces around the perimeter of the floor), we had a local metal fabrication shop make replacements using the old rusty pieces as templates. But I think it would be possible to purchase a 73-87 rear cross sill that's meant for the more common steel floor and modify it to work with the wood floor. That would basically involve cutting out a section across the leading edge, flipping it over, and re-welding it back in to create the recessed notch that the ends of the planks sit down into. The metal strips that go between the boards are available through Mar-K with the holes pre-punched for the 73-80 wood fleetside beds.