On a 1970, a b-body will have the steering box angled more toward the drivers frame rail, I assume to align the steering wheel with the dash that is angled in a 1970 b-body, straight dash in a e-body. It gets hard if there is not a coin welded to the front with the last 2 part # digits. If you put a bolt in steer box mount and compare side to side it is plain as day. In 1971, without a coin, hard to tell.