rbs56, I can't answer all of your questions as I have no way to confirm what these supports would have been called. Someone with access to the correct year GMC Master Parts Book may be able to help. Perhaps "Support - cab or cowl"??? I did some web snooping and came across a couple pics showing the support tubes I believe you are describing. One pic is noted to be a GM pre-production 1956 GMC Pickup with a V8 (1st pic below) and the second was described as a stock 1956 GMC Panel with the 6 cylinder (pic 2). Best guess is these were installed in at least 1955.2 and 1956 GMC's, but again I have nothing to confirm that beyond the pics I found.
As to them being needed, maybe yes/maybe no??? I saw lots of pic of similar year GMC trucks without them, but some engine compartments that hadn't been cleaned up/painted still showed where they had been mounted to the firewall. If you decide to remove them, don't get rid of them IMHO. Either keep them for potential reinstallation at some future date, or offer them up to fellow 'Bolters in the
Truck Parts For Sale forum.
