Jeep only moves in 4WD

Jeep only moves in 4WD


1984 CJ7 Jeep with 4" lift, 4.2L I6 AMC engine, 3 speed manual transmission, Dana 300 transfer case, Dana 30 front diff, AMC model 20 rear diff.
Went for a drive in the city today. Was backing up when the Jeep stalled (been jeepin for only 3 weeks now). Still had rearward momentum so I thought I'd take my foot of the clutch and try to kick start the engine back up. Engine started back up without a problem but lost all 2WD (forward or reverse). Rear driveshaft still moves but tires not going anywhere. Engaged my front wheel locks and went home in 4WD, no noises whatsoever, no problem going forward or reverse. Seems I must have firetrucked the rear diff. On inspection I found a fluid had leaked unto my rear right brake drum, fresh leak as it wasn't covered in dust. If I let the Jeep cool for a bit and try to move it in 2WD it will do so for a very brief moment, then loose all traction again. Any hints? Is it possible its only low in oil? Have I killed my Jeep?
Did the same thing once with my 1947 CJ2a . Rear is fried but in 4 wheel drive you are driving home on the front axle. Do you still have the AMC20 in the rear, if so you may have just spun the hub.
Spun a hub? What do you mean? Yes, this happened to me just today. AMC is still in the rear, haven't touched the darn thing since. By the way, thanks for your prompt reply. I was really looking forward to hearing from someone before going to bed...
The axle in the AMC20 is a two piece axle. It is a shaft with splines on both ends. There is a hub that slides on the wheel side and held on with a large nut. The splines between the shaft and the hub are easily striped. :(

Check out this link. The box in the lower left 2a shows the stock axle assembly. You nee to replace it with the one piece in box 1.

AMC Model 20 Rear Axle for Jeep CJ5, Jeep CJ7, & CJ8 Scrambler
GatorBate & Hole rule! Looks like I'm looking at a fix for around $400. Sheesh! Anyways... I suppose this won't happen again with a single piece axel? Thanks both of you for your input!
$400 is high unless you are paying for the rebuild from an outside service. The axles should be about $275 ( I paid 273.99 minus our ten percent discount plus $34.99 shipping ) when I bought mine from Morris.
If you can swing it financially consider doing any rear locker work while you are swapping axles. I think some outfits offer a Dana 20 package that includes axles and lockers, which MIGHT save you money IF it's the locker you want.

I'm not a serious off-roader but did stick a Lock-Right in my front diff because I was already rebuilding it. It was easy and it works very well. Haven't done the Dana 44 rear yet because I haven't had a reason to tear into it. My neighbor had a serious rock crawler that he beat in Colorado and he swears by Lock-Rights.

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