I already tried to get a build sheet from the dealer and their computer system wouldn't accept a vin from an '81. Which kinda sucks because i would have liked to know what was all spec'ed out in my truck. I tried that route when i was trying to figure out what axle set up it has since i need that info to be able to get new brake rotors.

 

You have brake rotors on the rear of an 81?

 

lol no but apparently they used a couple different brake set ups up front on the older rams. One was for a 3300 lb axle and the other is for something like a 3600 lb axle. Kinda confusing to be honest.

 

i would guess that you have a 3300# axle. never heard of 3600# axle. when i did mine there was 3300 Lb Axle and Except 3300 Lb Axle. my truck had a 3300# axle. if it is the wrong one i don't see why you could not return it and get the other one. the difference between the 2 i noticed is the rear bearing and seal size. if you want to try reusing the rear bearing seal you can remove the outer bearing and and put just the nut back on and then pull the rotor off and the wheel bearing and seal should pop out of the rotor.

 

sure looks like a 9 1/4 to me
http://cgi.ebay.com/ebaymotors/1981-...#ht_1662wt_939

 

Did the early 9.25s have a rounded upper edge on the cover? Pretty much every 9.25 i have seen on google has the stop sign shaped cover.

 

they could have. if you held up a ruler to the bolts you would still get that stop sign shape.

 

Every 9.25 I have ever seen, including the one in the provided link has a gasket that can be flipped top for bottom because the bolt patterns are symmetrical top to bottom. The picture shown of this rear sure doesn't look symmetrical top to bottom. Is it Darkrider?

 

Yea thats exactly whats throwing me off as well. Like i said when i think of a 9.25 i think of the stop sign shaped pan. and i can see what crazzywolfie means about the pattern being there in the bolts. Just not the pan itself, Half tempted to crawl under there again and reach up to the top of the pan to see if the diff housing itself has the stop sign shape or if its rounded up top like the pan is.