I asked a guy that sells and services lots and lots of vacuum wiper motors. He is unaware of any vehicle that used the same vacuum motor as our trucks but was also available with electric wipers.

If you don't want to tell us, can you give us a few more hints. This is kinda fun trying to find it, but only if you tell us in the end when we are thoroughly stumped.

•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-