TO-30 Starter Thrust Washer

Can you tell me what material the rear thrust washer is made out of in the original type starter on a TO-30.  October 21, 2016.

The thrust washer is steel. The part number is 1750440M1. I have these washers as well as just about everything else for the starter, and generator used on the TO-30. Let me know if you are interested in purchasing one of these thrust washers.