I think if the motor were original, it would be a Trico vaccuum operated unit. I believe the passenger side was an option.

Im betting the hole that is supposed to be used on your truck is the one on the right side of your pic. I think its about 14" from the divider strip in the windshield.

Did you ever get my email involving GMC COE part numbers?

Jeff


My 1953 Chevrolet
1947.1 Gallery
1972 C-10 1/2 Ton & 1972 C-30 1 Ton