I have an '82 Imperial and I'm trying to determine if it has a 7 1/4 rearend or an 8 1/4 rearend. Does anybody know what these cars came with? If not, how do you tell the difference between the two?
Thanks in advance, have a great 4th of July

i would say the 8 1/4 since it is an imperial i dont believe they ever came with the 7/14

71/4 9 bolt rear cover
81/4 10 bolt rear cover

if it's the size of a stegasaurus brain (walnut) it's a seven and a quarter.

http://www.moparts.org/Tech/Archive/axle/6.html check this link

Thanks! I went and checked and it's an 8 1/4

Sure Grip to come soon...

Hold the phone....10 bolts is not automatically a 8.25. There was also a 10 bolt 7.25 as well. My 80 Mirada had one, and I would bet some Imperials had them too.

In the pic notice they both have 10 bolts but the 7.25 has 2.5 inch axle tubes (most were 3 inch that stepped down to 2.5 at the housing)The easiest way to tell is the 8.25's cover is rounded while the 7 is more like a stop sign. 7.25 axle in front, 8.25 axle behind it.

From the side...

And then theres the other kind of 7 1/4 that has axle tubes that get smaller at the middle of the axle.

I agree an Imperial could easily have a 7 1/4" rear. Tons of Diplomat 4 door 318's did. Like was said above the tubes step down in size (so they could use the same sized axle pads and u-bolts as the 8 1/4") right before they go into the center section and those dumb things have 10 bolts too. The covers on them are pretty rounded if I remember right too to fool you at first glance but the step down tube size is a dead give away.

Ok, cool, I took another trip outback, and the cover is rounded, not octogonal, so that's an 8 1/4, correct?

The one that me and mopowergtx described has a cover that looks like the one in the picture. So if its round its probably a 8 1/4.