As stated the bad ground issue can make you crazy. Understand that all the tin on you truck is part of the circuit, so between a headlight bucket and the frame there are lots of places to get an open circuit. Extra ground straps from body to frame is also something to check.
Hang in there a keep checking you'll find the problem.


It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed