Dear Bill;
Don's correct; I'm guessing you ment this in the egines section.
The 'early' engines used a cast iron camshaft.
Sometime around 1954 they went to a steel one and and a steel distributor gear was made/from then on.
We all changed them (gears)'back then' on our Hot Rods because the racing cams were steel & they were easy to get (new) @ the Chevrolet Dealer.
Today It's not that big a deal. The iron one will work, but the steel one is better etc.
Good luck.
