Buoymaker,
The information you provided is not totally accurate with regard to the 64 & 65 Muncie/R10P OD units. None of the internal gears, syncro, and overdrive main shaft will interchange with the earlier models. They have a different pitch on the gears. In fact the transmission case is slightly different as the cluster gear is longer and will not fit in the earlier cases. There are two versions of this unit, a standard version and a more heavy duty unit with different gear ratios. This series is also referred to as a WG295.
The P case is also different as it uses a different (smaller diameter) governor and a different gear..
In addition many of the R10 H cases came with a rear mount.
Fred
