I have a 1972 C-10 with a 350 engine stashed away that is all original. I seem to remember the alternator being on the driver's side, with a bracket bolted to a raised boss on the rams' horn exhaust manifold, the same place where earlier models had a generator. If I want to mount an alternator on the passenger's side, I usually fabricate a mount from 1/4" thick 2" angle iron and 1/4" black pipe that straddles the front exhaust port and attaches with the two bolts for the exhaust manifold.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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