Just curious what rear this MIGHT have. It is a 1961 352, 2bbl, 3 speed? I am in 3rd around 20 MPH and I keep trying to find another gear. At 65, it sounds like it is working a lot harder than it should. IF it is still stock, is there some external markings to ID it? I haven't driven a 3 spd. in nearly 40 years, is this how they are supposed to run out?