12 bolt differential info needed

[HackJob65]

So I am rebuilding the rearend for my 65 which has the 64 style panhard bar and 17 spline axles.I had a 12bolt gov loc laying around and decided to use it and save some money. I bought new 30 spline axles and a 3.73 thick gear set to go on the carrier that had the ring from a 2.76 ratio on it. Being that the carrier was a gov loc I assumed it was a 12 bolt truck 3 series unit. Until I had bearings and gear mounted and dropped it into housing. The ring gear bolts hit part of the housing and even with all shims on one side backlash can be measured with a tape measure. So I removed from housing and set it next to the original. After some internet research I found dimensions for car and truck 12 bolt carriers according to the series. I have determined that this is a car series 2 carrier. Has anybody ever seen a gov loc in a car or did they ever build vans or trucks with a car housing?