You said the front diff has been opened? I'd check those ratios for sure then because that would cause your problem. If you are trying to push the front faster or hold it back as the diff diff's you'll feel pull from side to side amoung other things.

Frank.

I doubt that, as it would bind up with any motion. Mine does the same thing, and the front diff has never been opened. My rear has been replaced, due to a broken ring gear, with another stock 4.10. Mine does the same motion in the snow, and it was the same before I changed the ring gear as well. I think it is normal, but very weird.

There is an easy way to check to see if the front and rear ratios are the same. You don't have to take anything apart. Drive out to a dirt road in 2WD, stop and put it in 4W low, drive a few feet to make sure it is in 4WD, stop and get out and mark all 4 tires at top dead center. Slowly drive 10-20 feet trying not to spin any wheels. Stop and check your marks, they should all be clocked the same.

Of course if you have a lift you can do this test in the garage <img src="/forums/images/graemlins/notooth.gif" alt="" />

Ran out of time yesterday and had to put it all back together, but will be checking gear ratios front and back as this was the only remaining possibilty my mechanic and I could think of, he does not suspect the CV's since everything is nice and tight up there, tie rods, etc. It's not a huge issue just now since I don't use 4wd much, but will get it taken care of before winter. Really needed it in the snow and doesn't help to wrestle the steering just have traction. I'm considering which gear to change if it turns out to be different, if one is 4.3 might stick with it and replace the other, but no higher as I'm never going to lift much, would stick to 4.1 if so.

I have a friend in the VA4ROC with an 88 and he can drive fast in 4wd, Owners manual also specifies top speeds in 2wd and 4wd Hi match, up to 90ish in 5th - Impossible right now for my truck so something is definitely not right. ALso my 86 didn't do this, I could drive it pretty fast in 4wd and never feel anything until turning, then it was still not close to this jerking. Only some loss of power, this is Biiig power loss.
I took pics, they will be posted here when developed.

Well, then maybe it has something to do with VA 4Runners, then. I bought mine in Va in the '90's. It has done this since the 1st snowy drive. Interesting find on a trip to Minnesota, as I was trying to go down the snowy interstate more than 30 MPH, only to get yanked from the right lane to the left, and back again... All in under 5 seconds! <img src="/forums/images/graemlins/shocked.gif" alt="" />

I don't suppose you know if your truck was ever an automatic converted to a stick or anything like that? Would you?

What you're talking about doesn't sound "normal" to me at all. I drive over 60 MPH in 4HI on occasion with no problems like what you're describing...

It wasn't converted, according to the VIN it started as a stick shift and it still is.

Have you checked the ADD hardware and wiring?

They're manual hubs, one was kinda dry but both looked otherwise totally unworn, practically new. Put them back with lotsa grease. The 4wd lever itself had been removed and replaced, guy who installed my engine said it was in worng. It did shift much better but did nothing for the steering issue. We also checked the shifter action in the t-case, my mech said it shifted fine.

Actually "kinda dry" is better than "lotsa grease" in a manual locking hub. Too much grease can create a suction action preventing the hub disengaging or the grease can prevent it from fully engaging. I use either a very light film of grease or a spray of dry silicone lube in mine.