[EricH]

1) Typically, you don't. Most 6WD drop drivetrains are in a fixed location. A few are flexible--the center goes up and down and is locked in. I think 1323 put out a concept for that. 330 used pneumatic center tires and could adjust the pressure for what we wanted.

2) That's a design decision you have to make. It's a little bit smaller, so the same amount of torque results in more shear stress. The more stress you have, the more likely to fail a part is. 1/2" provides a bigger safety factor than 3/8" in this application. The question is, after doing the analysis, are you comfortable with the safety factor in the 3/8"? Or, to put it another way, does the reduction in cost offset the reduction in safety factor in your mind?