CodeTalker Posted April 6 Share Posted April 6 So, I'm new to this site, and MJs but not new to Jeeps. I've had several wranglers (3 TJ, 2 JK, and 1 XJ) I've wanted an MJ for a long time and finally came into one. I retired from the Army last year and my wife got this guy for me from a neighbor. It was the former owner's project Jeep, so not much is actually installed. If you could build an MJ from scratch (which I kind of am), keeping as many stock Jeep (don't care what model, just don't want overpowered aftermarket upgrades) parts as possible. To be used as a street queen with minor off-roading (body can't handle it anymore). What would you consider the best to install, from what model Jeeps and why? For instance, I pulled an almost complete radiator / cooling system from a 2001 XJ. Only thing I didn't think to grab as the cross brace on top of the radiator that holds in. I currently have: 4.0 I6 Manual transmission Transfer Case Cooling system (with additional electric fan) Miscellaneous interior / exterior parts. Things I would like: The stance (mentioned below) 4-wheel disc brakes Mostly stock looking interior, with bench seat Most stock looking exterior Automatic but not required I love the stance it currently has (without the motor though). The front is a Dana30, the rear, I'm not sure but the previous owner said he put it in just to be able to move the Jeep. I'll need a new rear diff. I'm not opposed to that being another brand (Ford 8.8 for instance). I'm not the best at writing up builds but I can try, if anyone is interested. Link to comment Share on other sites More sharing options...
CodeTalker Posted April 6 Author Share Posted April 6 Of course after posting, I saw this post: I'd still love everyone's input. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted April 6 Share Posted April 6 What year is the truck? Does it have any engine wiring? Link to comment Share on other sites More sharing options...
CodeTalker Posted April 6 Author Share Posted April 6 7 hours ago, Eagle_SX4 said: What year is the truck? Does it have any engine wiring? It's a 1987. I do have the wiring. Not 100% sure if it's for the 4.0 I was given with the truck, or the 2.5 that WAS in the truck originally. I believe the harness is for the 4.0. Haven't gotten far enough yet to go down that rabbit hole. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted April 6 Share Posted April 6 If the harness you have is installed in the truck, my guess would be it is for the 2.5 that came out of the truck. Look for the fuel injector connectors. If it is a 4.0 harness it will have 6 connectors that look like this. The hardest part of this build will be finding a complete 4.0 harness and computer. (Easiest route is buying a XJ to harvest everything from). Link to comment Share on other sites More sharing options...
CodeTalker Posted April 7 Author Share Posted April 7 I reached out to the previous owner. Turns out the wiring harness is for the 2.5. It's not in the Jeep. What year would you recommend I take the harness from? Link to comment Share on other sites More sharing options...
89 MJ Posted April 7 Share Posted April 7 36 minutes ago, CodeTalker said: What year would you recommend I take the harness from? My honest opinion is to use an LS and an auto from a 99-02 GM truck and trim that harness down. More power and likely better fuel economy than your 4.0 would ever do. If you like the 4.0, 91-95 HO would be a good option, 89-90 Renix would be a good option, and then the 87-88 Renix. I ranked them that way because a lot of people prefer the HOs, then the 89-90 Renix did not have the C101 connector under the hood and they had a better ECU that makes a little bit more power, and finally the 87-88 harness which has the C101 and the less desirable ECU. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted April 7 Share Posted April 7 If you are sure you are going to run the 4 liter, I would pull the harness and computer from a 91-95 XJ. The sensors are easier to find than the older Renix stuff (87-90). What year is the 4.0 you have? The engine date code is found on the side of the block as described in this post. Link to comment Share on other sites More sharing options...
CodeTalker Posted April 8 Author Share Posted April 8 The number on mine is 508MX02. This helps and is online with the harness you mentioned. Link to comment Share on other sites More sharing options...
CodeTalker Posted April 8 Author Share Posted April 8 On 4/7/2026 at 4:09 PM, CodeTalker said: I reached out to the previous owner. Turns out the wiring harness is for the 2.5. It's not in the Jeep. What year would you recommend I take the harness from? So instead of being lazy, I pulled the wiring harness out, and I counted six fuel injector connectors. Apparently the harness came with the motor after asking the previous owner again. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted April 8 Share Posted April 8 13 minutes ago, CodeTalker said: So instead of being lazy, I pulled the wiring harness out, and I counted six fuel injector connectors. Apparently the harness came with the motor after asking the previous owner again. Did it come with a computer? Link to comment Share on other sites More sharing options...
CodeTalker Posted April 9 Author Share Posted April 9 2 hours ago, Eagle_SX4 said: Did it come with a computer? It did but I was told it is bad. I don't know what "nad" means. Hard to confirm without the goods installed. I can still try to get a 1995 computer from a junk yard. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted April 9 Share Posted April 9 Good luck on the hunt for a computer. At my local junkyards the computers are the first thing to be pulled. Link to comment Share on other sites More sharing options...
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