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Unread 01-16-2014, 09:11 AM   #1
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1987 YJ Wrangler 
Join Date: Dec 2012
Location: inver grove heights, minnesota
Posts: 102
Np231 slip yoke question

Hey i have a 87 yj with an 88 np231 and found a sye on craigslist for cheap its out of a 2000 wrangler with a 231 j will this work in my np231? And i have the older style mechanical speedo will this still work with it because i know they switched to digital later on

I would support obama care if it covered my jeep too!
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Unread 01-16-2014, 09:34 AM   #2
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1994 YJ Wrangler 
Join Date: Aug 2009
Location: Ripon, California
Posts: 20,369
Its one bolt to swap the speedos
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Unread 01-16-2014, 09:34 AM   #3
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1989 YJ Wrangler 
Join Date: Nov 2010
Location: Sin City, Nevada
Posts: 2,881
Your good my 89 is mechanical

Sent from underneath my Jeep
89YJ 2.5L TBI, AX-5, NP231 SYE, Ford 8.8, Yukon Grizzly, Tom Woods Shaft, 33" BFG T/As, 4" lift, Warn VR10000s.

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Unread 01-16-2014, 10:33 AM   #4
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1992 YJ Wrangler 
Join Date: Oct 2006
Location: , Massachusetts
Posts: 2,750
A few things to look out for...
- Spline count. Your BA/10 tranny is a 21 spine output. Be sure the tcase you are considering is also a 21 spline.
- The front output yoke on the TJ tcase is for a CV (double cardan) driveshaft. Your YJ would have a single u-joint.
- The TJ tcase has an electric switch in the spot your YJ case has the vacuum switch for your front axle. Will need to deal with that if you still run the front axle disco with vacuum.
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