So it's important to keep in mind that not all scrap is alike nor suitable for all loads.
Some places shred, some bail, some just heap in chunks of crap.
Plus it's all era dependent. For example, odds are pretty low of finding ribbed back railroad wheels in a car in the 90s, then there's the whole vehicle thing too. Crushed 40s cars in a modern day gon are probably gonna be pretty rare.
The more you know, the harder this hobby gets!