I mounted a neck from a Squier Deluxe Active IV onto a Mighty Mite P-body. It was an excellent fit. However, when I tried to put on a neck from an older Standard P-Bass Special, it's heel was too wide for the pocket. I would've had to sand it out a bit for it to fit properly.
Most recently, I grabbed a Mighty Mite Jazz body. The neck I got for it is from a Squier Vintage Modified Jaguar Special (34" scale with black headstock and pearloid blocks) and I may need to shim it a bit. It's a little loose, but not swimming around in the neck pocket.
Aerodyne Club #47
Fender Owner's Club #18
Fender Blacktop Club #13
I felt a great disturbance in Las Vegas…as if thousands of Elvis impersonators cried out and then suddenly left the building.