frame identification

[dmacs66gmc]

Hi all!
I have been lurking on this site for a while and find it a very useful source of information.
I have a 66 gmc long stepper that I am restoring. Through the process I have come to the conclusion that the frame and rear end are not for a 66.
When I order parts for a 66 I am getting the wrong parts more often than not.
First thing I found is that the cross sills under the bed floor are thinner than a 66 should be. Also found differences in the emergency brake assembly. Seems like the front end is from the correct era as I have not had any issues when ordering parts. The pre bent brake line kit I just bought looks like it is for routing of the front to rear line on the drivers side. My frame has the break line running down the passengers side.
There does not seem to be a serial #on the frame just what I believe to be 2 part #'s on either frame rail. I have included pics of the #'s on the frame. Have also attached pics of the frame and rear end.
Thanks in advance to anyone that could help sort this out.

[Captainfab]

Your frame is a basic '63-'66 GMC frame. The GMC's did not have the VIN stamped into the frame as the Chevy's did. I do see the e-brake crossmember that is typical of the '63-'65 Chevy's. I do not remember if the GMC's kept that on '66. I can check a '66 GMC frame I have tomorrow. The rear end you have is a Dana 44 which is standard in the '63-'70 GMC's as well as leaf springs in the rear. The brake line is supposed to run down the passenger side of the frame to the rear. I'm not sure what the issue is with the bed cross sills that you received. All '63-'66 Chevy and GMC's use the same bed cross sills. Possible you were sent the wrong ones? Or maybe a PO changed the bed floor and it's crossmembers? Do you have pics of both?

[KenAdams]

Sounds like you just got wrong parts. Frame and rear look correct. There are also 2 different cross sills, the tall ones that support the bed and mount to the frame and the short ones that just support the bed and don't touch the frame.

[dmacs66gmc]

Thanks for the replies guys. Yeah it looks like people are just sending me the wrong parts. The rear cross sill I bought was taller than the cross braces that were on the bed so I had to modify it and make it shorter. I believe there was an inch of difference. Also when I got new box sides I discovered the PO had moved the rear fenders forward to line up with what I believe to be bed steps for a 55-59 truck. When I put the fenders in the stock position the side steps were too short. Was able to find a pair 60-66 bed steps and they fit perfectly.
I apologize for my lack of knowledge on these trucks and really appreciate this forum. I have restored a couple mopars but this is my first GMC.
I have included a pic of what the truck looked like when I got it(all green).
I restored the box and got it running the first year. The wife used it as her summer driver the first year while I contemplated restoring the rest of the truck. Last winter it was time to tear it down, repair cab rust and restore the rest of the truck. Looks like the wife will be waiting a couple years to drive it again.

[The Rocknrod]

Nice truck.