Either pull the driveshaft or just disconnect from the pinion flange.
I'll quote myself...I've towed my toploader equipped car for thousands of miles... and have never pulled the driveshaft. I've run 90+mph, and driven from where I life in central West Virginia to Columbus, OH... Norwalk, OH... Beech Bend Raceway on the far west side of KY. These trips range from 2.5hrs to 7 hrs each way. We're talking MULTIPLE trips to each destination. Never had a problem.
The correct answer and explanation...Either pull the driveshaft or just disconnect from the pinion flange.
The oil is only circulated when the input shaft turnsover the countershaft.
You can get away with short tows. After 5 miles start the engine & trans lube will be splashed onto the gears & syncros on the mainshaft. Bill
My brother-in-law said he never noticed that anything was wrong...if the towed cars transmission slipped into first gear, wouldn't you stop to see what was making the car pull so hard?