Just finished installing the shorter more expensive NAPA motor 655-1022.
Wow was that easy!
Absolutely zero modifications necessary, simple remove and replace. The two bolts lined up perfect, they were long enough and not to long, same with the 1/4" shaft.

Checked rotation on the bench and grounded the correct wire to the spare stud on the back of the motor.

Really really easy.

My truck is presently 6 volt positive ground, the 12V motor runs at what sounds like a "medium" speed. Later when I switch to 12V negative ground I'll unplug the wires and switch polarity, done.

Grigg

•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
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-