Whew, lots of info in this thread....Here's a bit more about the MS and MSB transmissions:
started life as the MS, with a bronze shift cone and steel
gear cups patterned on the very successful shift mechanism found in the VP sterndrive of the era. Later changes resulted in the MSB transmission with a steel
shift cone and friction marterial lined gear cups.
The engines that they were used on:
, MD5(all versions), MB10(gasoline engine), MD6, MD7(except last version which had the MS2 gear), MD11&17(except the last versions which had MS2 gears)
They were available in 1:1 and 1.91:1 ratio. Walters Machine even had an adapter which connected to the RV10 v drive to make a close coupled v drive.
Care is necessary if swapping units between the MD6/7 and MD 11/17 engines because the front casting is different between the two families. The MD6/7 casting had the input shaft in the center of the housing, and the MD11/17 casting had the input shaft offset in the housing, as seen in the foto attached to this thread.
The power flow within the transmission is basically co-axiel, with the input and output shafts almost in a straight line. (Slight drop center on the 1.91:1) In forward gear the power flows straight thru the box, but in reverse gear the power flows from the input shaft, across two idler shafts, and back to the output shaft. These idler gears are the cause of gear whine in reverse gear. The idler gear shafts ride in needle bearings, and a bad bearing could cause even more noise
The design requires a LH propeller
Hope this is helpful.