This just started on me. When in 4 (low or high), I'm getting a grinding from the tranny and the rear wheels are not locking in. It worked at first and then went out completely in about 10 min. The front works fine and 2 wheel there is no noise. I can swap it for another unit but before I go through that joy I wanted to make sure that there wasnt a link adjust or some other trick to try out first.

 

Thanks.

follow the linkage to the tranny and see if it is fully engaging.mine did that once and I couldn't get any gear, lots of grinding , thought tranny was toast. minor adjustment and it was all good.

Well the linkage turned out to be fine. The only adjustment I could find was in the High/Low selector. It was fine also. It goes into the gears fine including low range. The is just a spline slipping sound from the tranny when its under a load and in 4 wheel drive. The rear wheels dont push any at the same time. I guess I know what I'll be doing this weekend.

Drop the driveshaft out, and look at the splines of the yoke that goes into the tranny. While not a common thing, I have seen them strip out before. Usually caused by the front u-joint being siezed, or way overly stiff. Causes yoke to wobble slightly on output shaft, eating away at the splines in the front yoke.

Seen same thing happen in the slip-joint of 2-piece driveshafts, too.

I'll take a look when I pull it this weekend. I just barely put it in there and the shaft worked fine on the Push button tranny. The junkyard will swap me with another one so its no big deal. Just the time. It makes sense though.