Eagle

If the front drive shaft is spinning because of the locker, the CAD isn't doing anything for you. It WILL fail; it isn't a question of "if," it's a question of "when." Mine failed to engage on a below freezing day when I was trying to get to work through a heavy snow storm. Fortunately, I had a limited slip in the rear so by taking a different route I was able to get where I was going. The vacuum harness had rotted, so the CAD shift motor wouldn't shift. Like an idiot, I replaced the vacuum harness. The next time it fails (or maybe before), I'll just lock it in the engaged position. My Cherokees all have the factory Trac-Lok, which uses clutches. I have a TrueTrack in the '88 Comanche. It's totally transparent -- I don't even know it's there (except for the fact that I almost never need to use 4WD in snow). I think you need to check out your drive shafts.

The horror stories are mostly wildly exaggerated. The BA10/5 is not the ideal transmission of you expect to run huge tires and always hammer on the stupid peddle. Otherwise, driven more or less sanely, it's just fine. My '88 Cherokee has the BA10/5. It currently has a bit over 287,000 miles on it. Gear lube has been changed once in its lifetime. I've carried HEAVY loads from New England all the way to New Mexico. It's been off-roaded in Connecticut, Massachusetts, Rhode Island, Paragon in Pennsylvania, and northern New Mexico.

A decent snorkle arrangement will not use the factory air cleaner, it will use something that can provide a decent seal. Yes, it does. No good. See above. Time to start thinking about the aftermath. Didn't you just go through an engine swap to get your truck running again? Do you want to do that again? Even if you don't hydrolock it, every time you suck in mud you're effectively abrasive blasting the interior of your engine. You're going to destroy it. It's just that simple. Water on the top (outside) of the air cleaner wing nut is NOT your problem. It's a lot more serious than that. You need a good snorkle that will relocate the carburetor air intake up high enough that you won't be sucking in mud and water. You need something like this: http://www.rocky-road.com/jeep-cherokee-snorkel.html

A 31x10.50 fit perfectly under my shortbed. Can't answer about a longbed.

Leaf springs in front, passenger side drop on the transfer case, muffler in the wrong place, side mirrors don't look right. I'll take "No" for $1,000

I never have understood why drill sergeants act like ... drill sergeants. But, I don't understand why a lot of people act the way they do. Punch them? What a wimp. I went through Army Basic back when we still trained with the M14, which was a full-size battle rifle with a heavy steel action and a heavy wooden stock. During Basic my platoon's drill sergeant got in one guy's face more than the guy liked, so he grabbed his rifle by the barrel and swung it at the DI's head. The DI was lucky he saw it coming in time to duck, or we probably would have found his head in the next county. The DI took the blow on his shoulder, and it landed hard enough that it broke the walnut stock of the rifle. We were all amazed that the trainee didn't get court martialed. I'm glad, because the DI had it coming. He was what polite society reg=fers to as a Richard Cranium.

Snorkle

BlueXJ is correct. The early 231 transfer cases did not have a true neutral. "Neutral" disconnected the transfer case from the engine and transmission, but left the two driveshafts locked together. I don't remember what year they changed to a real neutral. Suggestion: Remove the driveshafts and then try pushing it. If it still rolls backward but not forward, your problem is in the brakes. My guess would be a dragging parking brake in the rear -- the drum brakes are designed to work better in the forward direction, and it's very common to see a parking brake that holds when the nose is pointed downhil but won't hold when the tail is pointed downhill.

I'm not sure about that because I let off the accelerator and put in neutral just to be safe. Like I said, I've driven several NP231's for years and never had this problem - I have noticed in the past that the T case usually doesn't like shifting on the fly when under too much power like climbing a hill, so I have always gotten in the habit of shifting not under load. DON'T put it in neutral. For shift on the fly you should be in gear, at "neutral throttle" -- which doesn't mean in neutral, it means balancing the throttle so you're not accelerating and you're also not coasting or compression braking. That keeps everything rotating at the same speed while you shift.

Yes, that there is what we call a "clue." Vacuum leak.

I think we have a winner.

If you can get to low range, the transfer case is functioning. And you're wrong on where the 4WD light is -- it's in the status light cluster to the left of the primary gauges. As already pointed out, your MJ has a vacuum-controlled axle disconnect. If you don't have good vacuum, it won't engage. The 4WD light is also actuated by a vacuum switch, so that's a second hint that you have a vacuum leak. You could try to track it down (which would be a good idea, since it probably also affects your cabin heating/ventilation distribution), or you could just permanently lock the axle in the engaged position. {Edit to add} I overlooked the fact that you said you have an '85. That's interesting, considering that there is no such thing -- the MJ was introduced in the 1986 model year. What transfer case does your MJ have? There should be a label on the driver's side sun visor that will say either "Command-Trac" or "Selec-Trac." The operation of the 1986 Selec-Trac was very different from the MP242 Selec-Trac of later years. The '86 would not have an NP231. If it's Commend-Trac it would be an NP207, IIRC. The 231 didn't come in until 1987 or possibly 1988. http://jeep.wikia.com/wiki/List_of_Jeep_transfer_cases http://www.4x4review.com/jeep-transfer-case-identification-guide/

265/75-15 is approximately 30.6" in diameter and 10.4" in cross section width. A 30x9.50 would be about 29.5" by 9.5", and a 235/75R15 would be 28.9" by 9.3". Long years living in New England have taught me that taller, narrower tires are best for carving through snow to get down to something approximating traction. I think either of the above alternates would be better than what you've got. The 235's will be less expensive. But, as has been commented above, the tread design will have a lot to do with how they perform in real snow. Real snow tires are far better than all-season or all-terrain tires, and mud tires are a very bad choice for deep snow.

I vaguely remember some discussion of the rear springs from the old, full-size Cherokee/Grand Wagoneer, which were SOA from the factory and had a fairly flat arch. Don't recall if they have the same length as MJ springs. Does anyone have specs for those?

It does okay. In fact, Hesco sells (or used to sell, as did Jeep) a conversion kit for that exact purpose. A friend of mine installed one in/on a YJ several years ago for a customer. Overall, you get an improvement over the stock 4.2L but it still won't be a 4.0L. The 4.2L has a longer stroke but a smaller bore. Long-stroke engines are good for torque but they don't particularly like to rev.

The AMC Model 20 in the XJ and MJ never had two-piece axle shafts.

You do realize that the Jeep catalytic converter is not a constriction, right? The exhaust front pipe is 2-1/2 inches, and the 2-1/2 inches carries through the cat. The connector between the cat and the muffler necks down to 2-1/4. It wouldn't have cost Jeep anything to keep it at 2-1/2 all the way to the tailpipe outlet, so there's a reason why they necked it down to 2-1/4.

It requires the same as any other diff -- buy new gears, buy new locker ==> install. It's a VERY heavy-duty axle, but heavy, and less ground clearance than a D44.

Considering that you can run 31s with NO lift, and that you don't seem to be planning any severe off-road use that will require extra ground clearance ... why are you even considering a SOA?

Yes, it will make a difference, and not for the good. Way back, when my '88 Cherokee 4.0L needed its first exhaust replacement, my brother was manager of a Speedy Muffler shop. So I took it to him, and he talked me into a 2-1/2-inch exhaust system and turbo muffler. BIG mistake. The 4.0L is a torque engine, and a larger exhaust hurts low-end torque while favoring high RPM power. The problem is, you're just not likely to be running a 4.0L consistently above 5,000 RPM. In my case, I could instantly feel the loss of torque and acceleration, but I have no way to document it. What was quantifiable, though, was that my gas mileage dropped instantly by at least 2 MPG under all operating conditions. Fortunately, the Speedy tailpipe and muffler didn't last more than a couple of years. Normally, I'm bummed when the exhaust system goes. This was the only time in my life I was actually hoping for the exhaust to die. When it did, I replaced it with an over-the-counter OEM spec 2-1/4" tailpipe and muffler from Auto Zone, and I regained my seat-of-pants perfomacne and my gas mileage.

Impossible. The differential is a percentage, so any difference increases proportionately to the speed. In other words, if the speedometer is off by 2 MPH at 30, it's off by 4 MPH at 60 and 6 MPH at 90.Not impossible, I don't mean to argue but I know for (edit: almost) a fact it's 7mph I don't know if something was messed up before but it's 7mph off I've driven by a radar sign and when my speedo says 55 it says 62. Now I realize there could be some error! So I did it again and it read the same! The radar could be off but who knows I would just be happy if it worked again! :) You can be off by 7 MPH when your speedo says 55. But that's the ONLY speed at which you'll be off by 7 MPH. When your speedo says 27-1/2, you'll be off by 3-1/2 MPH. It's a proportion, not a constant error.

Impossible. The differential is a percentage, so any difference increases proportionately to the speed. In other words, if the speedometer is off by 2 MPH at 30, it's off by 4 MPH at 60 and 6 MPH at 90.

So you're going to have between a 4" and 5" lift. You don't need a dropped pitman arm.

The ZJ pitman gives you about a 1-inch drop, not 4 inches. It also causes moderate bump steer. Generally not recommended. Why do you think you need a dropped pitman arm?

That'll buff right out. My brother's Nissan pickup broke like that. He found a shop that specializes in repairing such damage and had it stitched back together. It's probably stronger now than it was when it left the fatory.