Definitive towing specs on older C30
 

I have a 1977 GMC C&C dually, 454 & th400, 4.10's (I think), and a 10k GVWR. Is there any factory-published info with tow ratings on these older trucks? An extensive web search turned up nothing, figuring somebody here either has, or knows if they ever existed, a brochure or doc that shows the max GCVWR based on trailer type and equipment.