DougE wrote:
Shouldn't any 2wd manual transmission small pickup be towable 4 down?
No. There are output bearing lubrication issues for many modern manual transmissions. Nissan is OK with their 5-speed, and is Ford with the Mazda-sourced M5OD (which still wants a lube cycle at about 200 miles).
Upper shaft gears and bearings get lubed by splash from the countershaft. The countershaft is spinning only when driven by the input on the upper shaft. So the question becomes, how long can we run this bearing dry.
Your generalization works pretty well for FWD manual transaxles. The output shafts almost always spin the differential gears, and splash well enough to lube whatever needs it.
That being said, I know people towing 4 speed and 5 speed Toyota pickups from the 70's and 80's. When your small truck is 30-40 years old, you won't be having discussions with the manufacturer about what is or is not covered under warranty. If you break it, you fix it.