I worked on several of these "back in the day". They are pretty good units, but good lubrication is ESSENTIAL!! Unlike normal four speed transmissions, the Saginaw 3spd OD swapped ratios on the main shaft, direct drive being third gear and the normal 3rd gear being the overdrive. As a result, the back half of the main shaft spun faster than the input when in overdrive. The center bearing on the input shaft was subject to oil starvation and failure if the fluid became low or was contaminated.
We always slightly over-filled these units when servicing and used only premium lubricants. Today's synthetics are really the ticket when servicing them today.
