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Old 05-30-2007, 02:47 PM
Dean Dean is offline
Grease Monkey
Join Date: Apr 09, 2000
Location: Medford,Oregon
Posts: 270
Q. What is required to put 1978 axles in 1973 j4000?

Hi, a coworker is looking at buying a 1978 J10 with J20 axels under it and putting the axels in his 1973 J4000. I am going along for the ride (and leftover parts). What do we need from the doner truck besides the axels?
The truck is some distance away and time is limited on pulling parts.

TIA, Dean.
'78 Wagoneer Limited, 401/Q-trac W/low range. Mods so far, carter 4 bbl., rancho 3" lift, rancho RS5000 & RS9000,GB ign upgrade. '85 GW now with reverse, but great body. Donor rigs, '84 GW, '78 J20.
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Old 05-30-2007, 04:41 PM
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Tad Tad is offline
Join Date: Nov 30, 2001
Location: Out West
Posts: 17,618
Your friends '73 is a post mount suspension front and back, the '78 is not.
The front perches on the J20 axles are inset more and are for an SUA mouting, the '73 stock front perches are outboard more and SOA.
Two options there.
Add new perches to the J20 axle to mimic the placement of the perches on the '73 axle. Add hangers to the frame up front to mimic the 78 front spring hanger locations.
The rear should bolt up fine, perches may need to be moved but not as I recall.
I would grab all the driveshaft, brake and steering stuff that's there if that's an option also.

There's going to more to it than that but I wanted you to know the front axle is not just a bolt in deal.
2000 Infinity QX4, 3.3L, MPFI, 4 speed auto, 2 speed Nissan tcase, Unibody, IFS front, 4 link rear solid axle with 255-70/16s


...Pay no attention to these heathen barbarians with their cutting torches and 8" lift kits!...

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Old 05-30-2007, 07:01 PM
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Rande Rande is offline
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Join Date: Jun 26, 2000
Location: Winona, Minnesota
Posts: 5,489
Realize the '78 axle has disc brakes so the master cylinder and proportioning valve from the '78 have to go with the front axle. The front brake flex lines will need to be '78 items also. Not sure if the flex line fittings at the frame will be the same. The front hard lines may have to '78 also.

I ain't giving up. I've worked hard, it took me years to work my way to the bottom.

1998 Cherokee Sport (not maroon! Have history with maroon XJs)
1937 Chevy pickup (in progress)
1966 Mustang
1937 IH D2
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