87 Comanche Rock Crawler Project Hell

[AreWeThereYet]

A buddy of mine rescued this Comanche with some cool ideas in mind, but ended up pursuing other projects. After I started casually browsing rock crawlers, several hints were dropped that the MJ would be a great candidate, and I couldn't resist.

 

From what I've been told and am able to find out, it's a 1987 base model short bed that came with a 4.0 and a 5 speed manual.

Currently it has a 4.0 out of an 88, automatic AW4, NP231, and a low pinion D30 from a YJ on leaf springs up front. It runs well, shifts, and the 4x4 engages, but it's still a project.

VIN Decoding.

 

[89 MJ]

Looks like a good project. What do you have planned for it?

[AreWeThereYet]

The goal is to get it on the trails by the end of the year. I'm currently regearing the axles that will go under it to 5.13. The front is a HP Dana 30 trussed with WJ knuckles/ brakes, high steer, 4340 shafts, Spartan locker, and Warn lockout hubs. Rear is a 29-spline Chrysler 8.25, 4340 shafts, Spartan Locker, and will be converted to disc brakes.

 

Going to run 35s for now, build basic bumpers and sliders, 3-link the front,  put coil springs back on it then just new shocks/mounts in the rear.  It has a set of doors and a bed from another truck, but the bed is too nice for off-road, so I'll try to sell it and intend to build a simple flat bed similar to the one below. 

 

Dana 30

 

Flatbed idea

 

Doors and the short bed.

[AreWeThereYet]

I  got to drive it a bit last week after I found a deal on some Method MR 105 beadlocks with decent tires.

 

 

 

 

 

[89 MJ]

I think you've got a great plan there. Especially putting a 3 link in the front and ditching the leaf springs. 

[Big_Mark]

89 MJ beat me to it, leaf springs are not good for rock crawling, unless you like to hammer down all the time, which has it's place 

[AreWeThereYet]

Made a little progress and got the locker swapped to the new carrier and put the new ring gear on.

 

[ThatJeepGuy]

The traction bars on the rear (or what's visible of them atleast) is intriguing. 

 

Looks like a great start regardless the missing bits

[AreWeThereYet]

6 hours ago, ThatJeepGuy said:

The traction bars on the rear (or what's visible of them atleast) is intriguing. 

 

Looks like a great start regardless the missing bits

Thanks. The rear bars are Definitely intriguing, but a lot about this truck is. For now they’ll stay, and I’ll find a way to mount them to the 8.25 that’s going in the rear.

[89 MJ]

Seeing that pic of the rear suspension has me thinking there probably was a bad axle wrap problem. Those spring perches are awfully tall, but good for a little bit more lift.

[AreWeThereYet]

I was poking around over the weekend and found the engine date code: 801M20. If I understand correctly it was built January 20th, 1988 which means it came out of another Jeep, probably whatever YJ the front axle is from. Ultimately it doesn't make a difference other than I know someone put a good drivetrain in it at some point, just unsure of the mileage.

[89 MJ]

On 7/29/2025 at 4:59 AM, AreWeThereYet said:

If I understand correctly it was built January 20th, 1988 which means it came out of another Jeep, probably whatever YJ the front axle is from

It would’ve had to be from another XJ or MJ. The YJ didn’t get the 4.0 until 1991. 

[AreWeThereYet]

After a busy few months, some setbacks, and my ability to overthink and underthink everything, I now have the front Dana 30 regeared to 5.13 with a Spartan locker. Here's where my pattern ended up. Might be a tad deep, but I don't mind.

It definitely feels good to make real progress, and on one of the "more challenging" parts of the project.

 

 

 

 

I did the final assembly, and now it will sit until I regear the Chrysler 8.25 for the rear.

 

It will also be a big undertaking to get the axle under the front. Someone in this MJ's history cut up and welded on a bunch of mess to the front to add leaf springs. Most of it will be cut out, and I'll fab up simple spring towers, but the whole front bumper area may take some creative fab work.

 

 

 

 

 

On a side note, if you order from Revolution Gear, be wary of their master install kits for the D30. I ended up not having all the parts needed, and they didn't carry the missing baffle and oil slinger.

To their credit, the customer service was great and responsive, but didn't have a resolution for me, and basically said because they don't pack their own install kits, they have no control over it. The ring and pinion were great, it was just disappointing to order a kit that was described as having everything needed, then finding out it doesn't with no resolution other than to order missing parts from another vendor.