If you switch from vacuum to electric it's changing the vacuum diaphragm and mechanism on the differential and replacing it with an electric motor version, obviously the bolt spacing needs to be the same between the two different actuators.
I wonder if there is an electric replacement/upgrade for that axle?
If so I'd check trucks just new enough to have electric shift two speed, and hope that it interchanges.

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
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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-