My experience with salvage yard B30s is that very very very
few have them. I think they were stock only on the 1975 164te.

I've taken the timing covers off of many many B30s and seen
other B30/B20/B18 cars with the timing covers taken off, and
it's been my experience that only maybe 2% have the steel
gear.

That said, in the USA, or at least southern california, I was
able to buy a brand new aluminum gear from napa for $150 or so.
I've got it in my 164 and the gear makes no more noise than
the original fiber gear that disolved rather loudly.
chris