galled left rear axle spindle. repair? replace? buy used or aftermarket?

[ford38v8]

Huey, Ford rear axles are the same length from 1935 through 1941: 32.85". The gear on the inner end changed from 18 teeth to 16 teeth in 1939. Whichever gear number axle you have is matched to the set of two axles and spider. The axle you need to replace can be either/or along with the matched spider and opposite axle.
You wrote that you'll need to find a shop to do the job? Good luck on that, you're better off doing the job yourself. The kids in the shops nowadays only know how to work a cell phone. I would think you'd have already discovered that fact by now.