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The (IMPRACTICAL) Diesel Comanche

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Hey Everyone, Hows it going. 


I'm new to the forum. I joined the jeep world back in 2010 my first being a 04 5spd Tj Rubicon, then a 06 6spd Lj rubicon, finishing off with a 04 TJ Auto Rubicon. i always had a eye on the Comanches but never really know much about them. I sold all my jeeps Aug 2016 regretting it 9 months later. So Nov 9th i found a 88 Comanche.  i put down deposit site unseen. I'm glad i did it has to be one of the cleaned unibodys underneath ive ever seen. 


On the 11th i bought the truck and rented a uhaul and picked it up. Its a long bed and i love it for multiple reasons. I think done right they are sexy, Also I'm a motorcycle track day rider and my bike on its PITBULL trs mounting system  fits perfect with the tail gate up. Whats unique is that i live in a apartment complex so i rented 2 single car garages just for this build.

Deming this thread the (IMPRACTICAL) Diesel Comanche


The Build vehicle; 1988 Jeep Comanche Pioneer factory 4.0 Auto 2wd truck. 121472 miles on the clock. Super clean rust free underneath. top side does have surface rust but nothing that can't be easily addressed. Previous owner started doing a 94 HO swap but never finished. truck isnt running


The Diesel swap; 1982 Mercedes Turbo Diesel 300 SD 3.0 auto 82108 miles on the clock.  The Notorious OM617.


The Donor/Parts Getter;  1997 Jeep Cherokee Country, I will be using this to acquire all the parts for the Comanche build leading up to the front end conversion and tail light conversion. 


The Blue Prints;

Pull both engine out the Mercedes and the Comanche.

Physical Exam kit the Om617 by Mercedessource.com 

Swap in Om617

5spd swap.. NV3550

4wd conversion  HP30 front,  8.8 Rear

Transfer Case 241OR out of a 03-06 Rubicon

97+ front end conversion 

Paint - once all mock up is done + Color 2018 Calvary Blue.

00-01 interior swap with Creature Comforts- Modernized Electronics, 120 volt plugins for fast changers, heated steering wheel, heated bucket seats.










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On December 5th before the snow storm we just had. I found a 04 Jeep Liberty Renegade at LKQ.  With 3 hours till having to be a plus one at a wedding, i made it to LKQ dropped the Nv3550  with a hour 40 mins to go. Stock shifter which is uniquely bent seems perfect i might keep it that way. I will admit it was sketchy as hell crawling under this dropping a trans and transfer case. 



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4 hours ago, Pete M said:

moving this to Epic for obvious reasons :D 

haha thanks .. i wasn't sure if i qualified to be Epic..  this is a learning curve for me. ive been stalking builds inquiring much needed intell

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Yup, I'm in on this one.  It's got all the makings of something "Why did you do that????"


"because it can be done."


Shifter is epic.  Carry on.

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Nice project!


Here is a website that has some useful pictures on Cherokee/Mercedes engine conversions:




Northwest Diesel has been advertising these diesel conversions on Craigslist for a number of years.  As part of their conversion process, the Mercedes engine is rebuilt - that is the reason for the high price of their turnkey conversion.  Below is their ad.





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Still sorting out parts and building a list. 

Found a comanche 4wd front axle for 120 bucks should i get it? or just run a high pinion 30 from a cherokee .  Also found a 8.8 posi 3.73 for the rear, 150 thinking I'm gonna have to check that out.

Since the Snow. i was finally able to pick up my mercedes sd300 but its sitting in storage now since the Cherokee dropped a cylinder.

Did a compression test on it showing 140s across the board and 32 on cylinder 2. Since the weather has been crappy and ive work the last 10 days on 12 hour shifts I haven't had a chance to pull the valve cover to inspect the cylinder 2 rockers and valves.Hopefully its just that and i don't have a cracked skirt or a broken ring. that would put a wrench in this being aparts getter and she will have to go. Plus I'm thinking 00-01 solid black interior instead of the tan and brown but i do still like the over head console.

 So for tonight since its raining i decided to do a little test fitting to see how much room i have and what kinda bracket I'm gonna have to develop on the bottom side of the bed.there is a bracket that attaches to the latches that isnt pictured.. The Suzuki is gonna fit nicely.


See that dent on picture #2,  its ugly!! but thats literally the only big dent / body damage other then surface rust




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for sure use the xj's dana 30 high pinion, but double check the rear axel as well i'm not sure but i think some came with an 8.25 rear. Something about it being a "country" makes think its a good chance its got a beefier rear axle. and if it is you should be able to run it with out re-gearing. my memory is foggy but i seem to recall that that you want to run higher gear s with a diesel an account of them having more torque

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