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m38a1 flywheel. I have a 1953 m38a1 motor i,am rebuilding and a 1967 m38a1 motor for parts, the 67 motor has a 12 1/2 flywheel and the 53 has a 13 in. The bell housings and starters are also different, anyone have suggestions ,why.

The flywheels are the same. The ring gear causes the difference in diameters. You need to count the teeth on the ring gear. The correct F134 flywheel ring gear for the M38A1, CJ3B, CJ5 & CJ6 is the 129 tooth which gives the largest overall diameter. The correct bell housing for this flywheel two half inch diameter starter mounting bolts. The smaller 124 and 97 teeth ring gears used the bell housing with the 3/8" diameter starter mounting bolts.

I'd guess the motor that had the smaller flywheel had been installed in an earlier flat fender jeep like the CJ3A. M38 or CJ2A.

The bell housing that was with this flywheel has a bushing for the starter in the bellhousing, are the m38 and m38a1 starters different, there was no starter on this motor when i bought it from CROWN ASSETS, motor had been rebuilt in 1983 when still used by Canadian Army.