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post #1 of (permalink) Old 12-06-2000, 03:26 PM
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AX-15/NP-231 in a CJ?

Howdy. A buddy of mine is thinking of rebuilding his old CJ-5 that has a 74 model 4.2 liter 6 but no tranny or t-case. He wants some good low range options, but doesn't want to spend a lot of cash. A T-18 with a Dana-300 would be ideal, but would be very expensive. A rebuilt T-18 costs $1000 alone, with another $200 for a D-20 and even more for a D-300.

Anyway, how would an AX-15 and NP-231 work on a CJ? The AX has a reasonably low first (just a bit higher than a standard T-18's) and the NP-231 has a better low range than a D-20. And (I'm getting to the question) they're so common that I would think you could buy a used tranny/t-case setup for not much.

And are they strong enough for a rig with 33" tires and lockers? I've not heard of people having problems, but the aluminum AX and chain drive NP aren't the tractor tranny that the T-18 is, for instance.

Oh, yeah, there's the other question--I know that this tranny was used on the 258 in the YJ and that the 4.2 and 4.0 blocks are very similar, but will it bolt up? If it's not a direct replacement, what is involved? Thanks!

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post #2 of (permalink) Old 12-06-2000, 04:01 PM
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Re: AX-15/NP-231 in a CJ?

The AX-15 and NP-231 will take any 6-cylinders power just fine, and will hold up to practically any tire size you can fit on a Jeep. The AX-15 will bolt to the 4.2L with no problems, but the NP-231 has a driver's side front driveshaft while all CJs use a passenger's side front driveshaft. A Dana 300 should be able to bolt to an AX-15 though. I know the bolt patterns are the same but I'm not sure if there would be any other clearance issues.

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post #3 of (permalink) Old 12-08-2000, 02:41 PM
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Re: AX-15/NP-231 in a CJ?

I am putting together a Scrambler for my wife to drive, I found a 4.0, a AX-15, and I am going to use the D300 X-fer case. AA has the adapter, but I found another source thats cheaper..R&P 4 WD Parts Inc. makes a steel adapter to mate the AX 15 to Dana 300. I think it is less than $100.
Give them a call at 503-557-8911.
Bob in Ma

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