This was one of the lowers that did not leave Bushmaster as a complete firearm,
it is in the L059000 series, which fits in:
L051001-L063000 - Mixed Pre-Ban Assembled Rifles and Pre-Sept 94 Lowers
I still have the receipt from the dealer I purchased it off of though, which has written on it "pre-ban bushy lower" and the serial #.
Thank you everyone for your interest!