No stamping that I can find and I've checked multiple times. I was on Brewer's website and it shows numbers should be on the reverse lever. I sanded it down and there's no stamping there.
The chrome lever looks as though it's an integral part, not like the more common bolt on handle. Someone cut it off and modified it to accept a bolt on handle. I'm pretty unfamiliar with 4 speed stuff, always ran automatics but would like to convert my Duster over at some point.