The tails are all the same length unless it was a 4wd or some motorhomes from what I understand. However, the trucks used a stiffer tail housing, and the access port to get to the retaining clip is on the side of the housing. That tail housing will not fit an A body chassis. So you need the passenger car tailhousing, which may have been on your truck trans. I've seen that a few times too. If the steel plate with 2 large phillips head screws is in the bottom above the mount, you're fine. If it's on the pass side facing straight out the side, replace it. The mainshaft is the same..just the tail housing is different.