you may have a little trouble just bolting up that drive shaft and also some(most) internal parts are different so keep that in mind for future service of the diff <IMG SRC="smilies/biggrin.gif" border="0">
You will have to redrill the flange for the larger bolts and different pattern they used starting in 84. Just take a flange from an 84-up diff, pull the thin metal cover for the pinion seal off. Then use a hose clamp and clamp the newer flange to your 83 flange and drill 4 new holes. Then you will have a dual bolt pattern flange. Just make sure that the drill bit is the same size ( bolt are metric and bits you have are most likly standerd ) as the new bolts. Leave the newer flange clamped the the older one for a guide. Splines for the axles are the same. Btw you can leave the 83 flange on the third when you drill it out. You only need the remove the cover on the 84-up flange because it gets in the way of the drill.
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