Both trucks are running poorly when cold, and the Chevy's been backfiring sometimes. The Ford was leaking oil pretty badly.
He had me put a heater core in the Chevy, spray the carb down with cleaner, and do a little diagnostics. I found some oil saturated vacuum hoses, which had turned to mush, a vacuum leak, and a sticking, leaking EGR valve. I didn't yet pinpoint the exact cause of the backfire, though it may be the carb. That also might be the cold running problem, though it did OK today after-noonish.

tightened the valve covers on the Ford and gave the engine a bath, changed the plugs and dist cap. Need to re-adjust the carb on that one too, i think, and look for some good vacuum diagrams of the heater system. I'll be going back probably Thursday.