[markjohnson]

I wouldn't worry about an aluminum driveshaft. Sure, they look neat but the the cost per benefit is not very beneficial. They end up being so thick-walled to match the strength of .083 DOM steel tubing that it's just not worth it. Also the U-joint cups like to gall up in the weld yokes. Spend your money wisely elsewhere, like towards one of those brand new M-22 Muncies after the pain you're going to inflict upon your current M-21 with a new high HP/torque motor!