OK I found it

74-77 D100-200-300

Arm, Steering Gear

3492214 Power

3492213 Manual

I cannot guarantee the accuracy of this info, it's only what I read in the manual.

Note initially I thought you might have a hard time finding this but they are on eBay aplenty and may have been used thru 1993, you may be able to buy one from Ma?

Red