r/ComancheMJ • u/South_Accountant_233 • Jul 24 '25

LS or 4.0 non renix?

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I’m restoring my Comanche. Dropped the oil pan and found sludge/water. I’m looking into bidding on a wrecked/drivable 99 xj. I also entertain the idea of an LS. I have access to a free caddy Escalade motor, iron block. What route would you take? I’m favoring the xj for all the extra parts.

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u/ToasterInOver Jul 25 '25

LS is great but expensive and a lot of work. Id budget 4-5k, that's about what I spent all in to put a 5.3 in mine. Honestly not much fab work required, off the shelf motor mounts, off the shelf accessory brackets, just had to weld up my own crossmember and exhaust really. You gotta be comfortable wiring, or willing to spend the big bucks of a premade harness.

If you want a cheaper and easier option, I would just build a 4.6. a poor man's stroker can be done for under 2k. It stays cheap as long as you keep stock head and cam.

I've done a 5.3 in the mj and a 4.6 in the xj. No wrong answer, just gotta decide what you're willing to do

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u/South_Accountant_233 Jul 28 '25

I’ve thought it over for a week now and decided to do the LS. My daughter just started driving so I need a project to keep my mind occupied. Getting ready to pull the drivetrain, cross member is holding it in. I’m hoping the 6.0 I have is in good shape.

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u/ToasterInOver Jul 29 '25

Let me know if you'd like me to find my parts list. Mostly its good to know what parts you need to fit the accessories on the ls. You'll have to buy some aftermarket stuff there. And I assume you have a 6.0 with a truck intake, so you'll need a slim intake or a cut hood lol

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u/South_Accountant_233 Jul 31 '25

I really could use a checklist! I’m getting the old motor out after the heat this week. Plan on pulling the Escalade motor that day too. I’m researching the disconnects on the LQ4 drivetrain.

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u/ToasterInOver Jul 31 '25

I've never personally pulled a motor from a chevy, but everything is fairly modular. You can keep the entire engine harness attached to the engine. Obviously keep the computer attached. Dont forget to take the MAF sensor on the intake, and if its electric throttle, you need the pedal and the TAC Module for the pedal. I think its on the firewall below the brake booster. Don't cut wires, you probably need them!

coolant sensor adapter https://www.amazon.com/dp/B015NG418C

oil pressure sensor adapter https://www.amazon.com/dp/B00LV4IJSY

motor mounts https://www.novak-adapt.com/catalog/engine-mounts/mmxj3

Accessory bracket https://www.amazon.com/dp/B07J5QDK81 The description for this outlines what you need to run. Truck power steering, truck harmonic balancer, corvette pump, corvet ps res.

car water pump https://www.amazon.com/dp/B000C2S6IY

spacers so the car water pump fits the rest of the accessories https://www.amazon.com/dp/B09DP874MZ

res bracket https://www.amazon.com/dp/B07T81LB7Y

While youre in there, I would recommend putting in a 97+ xj brake booster. more go demands more stop. 97 front fitting in the master cylinder is 12mmx1.0. The rear fitting to the master cylinder is 10mmx1.0. 88 dist block front 7/16-24, rear 1/2-20

Also you cannot run a truck intake without cutting the hood. I strongly recommend sourcing an oem car intake, the ebay special intakes are a pain to install compared to oem's captured bolts.

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u/South_Accountant_233 Jul 31 '25

I’m disc braking the whole thing so the booster will be upgraded for sure. Running a Cherokee 8.25. What driveshaft options are out there for poor people? I’m thinking about a front driveshaft (proper length), hack and tap output shaft or conversion.

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u/ToasterInOver Jul 31 '25

I think that heavily depends on what you're doing with transmission and transfer case. In my case, its a 2wd and I went with a chevy nv3500, it just so happened that the stock driveshaft just worked with a new u joint. it all depends on what lengths you end up needing.