Is there more than one gear ratio on amc eagle rear ends?

[wampus_cat]

Hello all, its been awhile since I picked your brains ;p
I gave up on the motor on my '85 eagle.  I recently purchased an 84 eagle sport 4door wagon, with a shot rear end.  I removed and installed the rear end from the  85, and I am worried about gear ratios, Is there more than one available?  I test drove it already, and it seemed like I was going a lot faster than the speedo said. 
Thanks for any input
Also, what makes it a "sport"?

[IowaEagle]

Yes, there are different rear (and front) ratios.  They have to match or you will destroy your viscous coupling.  I think in '84 and '85 the 2.35, 2.73 and 3.08 ratios were offered in automatic transmission 6 cylinder cars.  There is a tag on the front differential (unless removed) that gives that ratio and a stamping on an axle tube boss on the passenger side near the pumpkin cover with a code:  L = 2.35; J = 2.73 and F = 3.08.

The 1984 wagon sport package contained:  Blackout moldings and accents; black bumpers with guards; Left remote sport mirror (black); Halogen headlamps and fog lamps; leather wrapped sport steering wheel; 4 X 4 graphics; and from the factory P195/75 R15 BSW Arriva steel radials.

[wampus_cat]

Thank you, that is what I was looking for.  Fortunately, I have the front diff out of the donor car.  So after I change the front diff, my speedo will be massivly off, according to gps 23 on the gauge = 30 real mph, 43 on the gauge = 55 mph.  Is this adjustable, or change-able?

[IowaEagle]

It can be changed with a different speedometer gear.  Get the one out of the donor car's transfer case and replace the one you are using now.  Make sure you note the position of the adapter housing on the donor car so you can line up the marks on the car you are putting it in.

[carnuck]

Sounds like the sport originally had 3.08 gears. If you don't want to change the front, search around for an '84-'90 XJ with 4.0L 5 speed. Most are 3.08 and except for the shock mounts, they are bolt in plus that gets rid of the 2 piece axles. Already have one going into my wagon once I feel a bit better.

[wampus_cat]

Two piece axle?
I already changed the front diff yesterday, the one I took out had a vacuum controlled, I assume 4x4 switch, and the one I put in did not.  I will have to figure out how to eliminate the unneeded vacuum lines, always I good thing I say.  Now instead of 8 miles there is only 7

[carnuck]

2 piece rear axle. That big nut in the middle is one of the weak points of the Eagle's D35/Model 15 rear diff. The other is the small pinion bearing with a heavy side load.