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Donor truck for axle swaps -- Is there a Holy Grail?


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As seen in my sig, my truck has the dreaded 3.07s and rather than sink bux into the engine, which runs well despite its age, I want to regear. However, out here on the Left Coast pick-a-part axles are thin on the ground and pretty pricey to boot, and I want to do this on the cheap.

 

I'd like to keep a D44 in the rear, as I carry camper weight, so I guess my question is there an XJ (or MJ or other model) that would give me an HP D30 Fr./D44 Rr with 4.10 or lower (4.56, 4.88) ratios that would have the proper WMS so that, other than repositioning spring perches, the swap would essentially be drop in and bolt up. Extra points if it'd have a D44 rear (or something sturdier than the D35, eliminate the CAD and have 297 joints. Extra extra credit if it had disks on the rear. I suspect that with those ratios, the engine would be a four banger, but I'd be looking to part out the remains anyway.

 

One other query: I've heard that the front gears on XJ spin opposite from MJ. True? And if so, does it matter and how to fix if it does.

 

One final query: Anything else I should be specifying in looking for Holy Grail axles, like lockers?

 

Don't want much, do I? :brows:

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I'd like to keep a D44 in the rear, as I carry camper weight, so I guess my question is there an XJ (or MJ or other model) that would give me an HP D30 Fr./D44 Rr with 4.10 or lower (4.56, 4.88) ratios that would have the proper WMS so that, other than repositioning spring perches, the swap would essentially be drop in and bolt up. Extra points if it'd have a D44 rear (or something sturdier than the D35, eliminate the CAD and have 297 joints. Extra extra credit if it had disks on the rear.

 

4.10 - used with 2.5L engine usually, and older XJs with the "Off-Highway Vehicle" package.

92+ dana 30 has no CAD

Dana 44 non c-clip - 30 spline, 1.31" diameter shafts, 8.5" ring gear, 2.75" axle tube - used 87-89 on XJs equipped with towing package.

Ford 8.8 With Disc brakes - To get rear disc brakes and 31-spline axle, you need to look for a 1995 to 2001 Explorer or Mountaineer.

 

One other query: I've heard that the front gears on XJ spin opposite from MJ. True? And if so, does it matter and how to fix if it does.

False. Standard cut gears are for Low pinion axles, reverse cut is for high pinion axles. The Low vs. High refers to the pinion and its center-line in relation to the axle shafts.

 

One final query: Anything else I should be specifying in looking for Holy Grail axles, like lockers?

 

No D30 will have stock locker or LSD and google.com is your friend

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Any 1997 or newer Cherokee 8.25" axle is a good choice, almost equal to a D44 in some aspects, better in others. Beware, though, as even in those years a lot of them had D35 rear axles. Pretty simple to relocate the spring perches with an angle grinder and a large welder. It is also trivial to swap ZJ D35 disc brakes onto this axle. The only needed modification is drilling out the center hole from 2.75" to 3" to fit around the larger axle tube.

 

D44 from early Comanches or Cherokees is difficult to find and usually fetches a premium price.

 

Ford 8.8 is lauded by many, and fits pretty well under a Wrangler or Cherokee. The Comanche wheel wells, however are a bit wider in the back, and the 1" narrower axle will cause interference problems with the inside of the fender unless you use wheel spacers. 1995 and newer had disc brakes, and 4.10 ratio is pretty common in these. You will also need to get a 1310 flange for it, or a 1310/1350 conversion u-joint to mate your driveshaft to one.

 

D35 is fine as a boat anchor, but not as an axle under a vehicle.

 

High pinion D30 is easiest to find under a Cherokee, and were used I believe through 1999. 2000 and 2001 are low pinion. Any with anti lock brakes had the 297 joints, 1997 and newer has 1997 regardless of brakes. Selec-trac models (with the 242 transfer case and full time 4wd capability) didn't have a CAD. 1992 and newer not have one regardless of transfer case.

 

Other D30s that are a straight swap in are under ZJ Grand Cherokees and TJ Wranglers, but IIRC, these are all low pinion. YJ is high pinion but leaf sprung.

 

4.88 was never offered from the factory.

4.56 was available from the factory under some early 80s 4 cylinder/automatic transmission. Very rare.

4.10 is very common under 4 cylinder/5 speed, and all later 4 cylinder regardless of transmission

3.55 came with earlier 4 cylinder/4 speed and 6 cylinder/automatic

3.07 came with 6 cylinder/5 speed.

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I'd like to keep a D44 in the rear, as I carry camper weight, so I guess my question is there an XJ (or MJ or other model) that would give me an HP D30 Fr./D44 Rr with 4.10 or lower (4.56, 4.88) ratios that would have the proper WMS so that, other than repositioning spring perches, the swap would essentially be drop in and bolt up. Extra points if it'd have a D44 rear (or something sturdier than the D35, eliminate the CAD and have 297 joints. Extra extra credit if it had disks on the rear.

 

4.10 - used with 2.5L engine usually, and older XJs with the "Off-Highway Vehicle" package.

92+ dana 30 has no CAD

Dana 44 non c-clip - 30 spline, 1.31" diameter shafts, 8.5" ring gear, 2.75" axle tube - used 87-89 on XJs equipped with towing package.

Ford 8.8 With Disc brakes - To get rear disc brakes and 31-spline axle, you need to look for a 1995 to 2001 Explorer or Mountaineer.

 

One other query: I've heard that the front gears on XJ spin opposite from MJ. True? And if so, does it matter and how to fix if it does.

False. Standard cut gears are for Low pinion axles, reverse cut is for high pinion axles. The Low vs. High refers to the pinion and its center-line in relation to the axle shafts.

 

One final query: Anything else I should be specifying in looking for Holy Grail axles, like lockers?

 

No D30 will have stock locker or LSD and google.com is your friend

 

2000 & 2001 XJ's used low pinion standard cut front D30's.

 

Although hard to find, some '60's app D30's did indeed have a factory power-lok LSD. Very rare. The D30 was also used sporadically as a REAR axle during this era.

 

Agreed that for the price, the 29-spline 8.25 gives up almost nothing to the D44 in the real world except availability of parts. Both exceed the strength & capabilities of the tiny D30 even with 297 joints. pick say a '98 XJ and get it all in one package for cheap, although the 4cyl versions of that era are a lot more rare. 4.56 & 4.88 ( use caution here as the pinion on 4.88 D30 is said to be an issue) would probably require a R&P swap. You can get a HPD30/8.25 gear package for about $500 and about $300 most places for someone to install them.

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Go on cars.com and look for either the XJ 8.25 or Ford 8.8 with 4:10's. Finding any lower gears for rear won't be so hard however finding a Dana 30 with lower gears and HP will be VERY hard. A XJ/MJ rear Dana 44 is kinda hard to come by, kinda pricy, and VERY hard to find with 4:10's. Also finding a 4:10 geared ford 8.8 with LSD should be very easy todo.

 

You "should" beable to find and put in both the front and rear axles for $600 and under. However things like this tend to nickle and dime people to death sonwatch out and good luck.

 

Brandon

 

Oh and yes there is one car with every thing you might want that would be a XJ 4 banger newer, auto, with the 8.25 in it. But always check gearing befor just assuming what you have.

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Thanks so much for all the great advice. It'll take me a while to digest it all, but I'm going down to Baja for a few weeks, and I'll lay in the hammock and think about all this as a winter project (while drinking Turtle Beers and having sun-darkened topless maidens in short shorts bring me shots of the finest tequilas through-out the day)!

 

Y'all enjoy winter now! Changes of seasons and all that. :brows:

 

Appreciate all the suggestions!!

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