A Chevrolet radiator support is braced with cross rods in front of the radiator - a GMC is not, and the radiator sits inside the support (the reason there's a gooseneck radiator fill on the GMC)
If you are fitting an LS engine with the truck accessories, you're going to need all the room you can find in front of the water pump. A GMC radiator will give you 1-1.5" more than a Chevy. This is the radiator in my 49 GMC and it is almost flush with the support.
I used a US Radiator -
https://usradiator.com/product/gmc-t...minum-radiator
It can be configured specifically for the LS with a steam port installed.
I built a fiberglass shroud for mine and installed a 17" high CFM SPAL fan. The fan is controlled by the ECU. Here's a photo of the assembled radiator and shroud (shroud isn't painted yet in this pic - still sanding it down. Note location of the inlet tube for the LS motor
