I'll just copy/paste parts of the email I sent the company. I am looking for as much feedback as possible.

I just had product #500 installed today at a 4x4 shop.

It seems difficult to engage or disengage when moving below 10mph in 4HI. I did try moving it in 2HI and while it did work somewhat quicker and smoother, I heard a brief groan noise coming from the front axle upon engagement (doesn't do that in 4HI), which concerned me (But the 4WD did work after I hit the 4HI button). To make it engage, I put it in 4HI and I have to pull hard to try to engage the front axle. Eventually it does lock in while I am pulling it with the car moving. If it is just one notch off, the front wheels don't lock in. Basically the width of my thumb must fit completely on the metal behind the handle for it to be considered a lock. To unlock it, sometimes, I have to back it up or move it forward while pressing the button firmly until it fully retracts to it almost fully retracted position (it does have a thin space when it is unlocked, which I was told is normal).

Following the instructions, it seems that I have to roll the car a long distance while pressing the handle hard or pulling it hard just to make it disengage or engage fully. The shop did install it using the instructions and showed me how to use it and it seems to move smooth other than the end zones. Do I have an issue here? How do I fix this? I already had to have the front differential rebuilt (shift fork and collar replaced) just after we bought this car (It was broken and we did not know it) and I really would not want to break it and have to go through that again. I also would not want to be stuck with the truck in 2HI and not be able to get the front wheels locked in because it has to be moving. Thanks for your help.

 

Is there I chance that something is broken AGAIN in the front differential? The 4x4 is working after getting it engaged, but the problem is getting it there and also disengaging it. I also just changed the fluid a few weeks ago with Lucas 80W-90. I did find a little bit of fine metallic "glitter" in the bottom of the drain pan once I drained the gear oil and ATF (I also did the transfer case), but I didn't find any major chunks or anything like that. I had the rear diff and transmission done and there were no problems found. As I said before, it works a little easier trying to engage it in 2HI than 4HI, but I hear a noise when I do it that way. It doesn't do it when trying to engage it in 4HI. Am I causing damage here? This thread may sound crazy, but the last thing I would want is to have to repeat the repair on the front diff, which involved replacement of most the parts related to the engagement mechanism and bearings and seals.