Hesitation/slip at takeoff

[Cornfield creations]

on my 98 k-1500, here recently it does a strange slip or hesitation when immediately taking off. It feels like the wheels slip, then suddenly grab. It started when the outside temps dropped.

I thought maybe my trans was acting up, but I put it 4hi and it wouldn't do it, so that lead me to the rear end.

About 4 months ago I put new u-bolts, new bushings in the leafs, and new shackles. I checked the lugs and the u bolts, and it was all good.

Any ideas?

 

[Fordum]

If its an automatic, it sure sounds like the transmission. Why it would not do it in 4hi, I have no idea.
If it were a newer model, I might think that shifting it into 4hi would effect the line pressures, like in some of the computerized shifting transmissions.

But I don't think yours has any of that stuff.

I don't know of anything in the transfer case or rear end that could do that without either a lot of noise or doing it all the time.
You mentioned that it was doing it when the weather was cold. I don't suppose you are parked on ice????
Your best bet is to have someone stand alongside the car and watch the rear axle when you start off.
I have seen the axle slide along the leafs when the center bolt was sheared, but usually you can see signs of it when you look.

Also, chock the wheels and try turning the driveshaft to see if you can find any play.

 

[Cornfield creations]

It will do it for many take offs, not just one, but later in the day if its warmer it won't do it. It's strange to say the least. I thought also the u-joints might be bad, they are original, but they are tight.

It has 194,000 miles on it. When I bought it at 181,000 miles I changed trans fluid, and it was dirty, but not that dirty. I know these trans last about 120,xxx. So I am assuming it has been replaced, even though I have no documentation.

I thought maybe the rear end has some slop in it, and it's time to pull the cover off, but to me still doesn't sound like the diff. to me.