If gears do turn out to be worn then what will you do? Very unlikely to find new ones. Do you have a spare transmission for parts?
If you don't have or can't find parts there's no need to send it out for a rebuild.. Unless you're up for having gears custom made?

Old auxiliary transmissions made some noise to start with, yours may still have issues but they were never silent.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-