Everything is explained in the video. Thank you in advance for your help. This is the best forum on the Internet.
AFAIK your axles are '70 - later while those drums are '69 - earlier... None of the numbers on carrier really mean anything, just casting/mold info that could be used in anything, zero info on brake parts... Specific application ID is on a tag that's supposed to be attached under one of the carrier nuts...
71-73 drums are different than 74-77 drums...so are the wheels. You need late model drums to fit the late model axle...and late model wheels