Looking through some of my alternators today and realized one of the open face alternators has absolutely zero stamping on it. im guessing this is a replacement? I am including pictures of two alternators, one with the manufacturer stamping and the other one with nothing.
any input on this?

 

The first unit looks like one I bought on eBay, I’ve heard this open frame alt was used on forklifts..

 

Olds open face alts had were internally regulated and had different backs.

 

The first one with the larger pulley and no number looks like an aftermarket open face. Notice how thin the lip is where your thumb is compared to the other one. The automobile open faced all had this thin lip. The other one is an industrial style. It has a wider lip, but not as wide as non openfaced ones.

 

Thanks for the info.
If I remember correctly these were both in the trunk of a 70 cutlass I had several years ago.