Tranny/rear

I'm having a serious rattle vibration when driving on level ground when crusing at speeds above 40. The sound comes and goes in rythem it is hard to pin point while driving but it does not sound good. My truck is a 98 K1500 silverado with a 4l60E trans and a 10 bolt rear. :swear:

quite likely it could be bad U-joints, and thats what you should hope for cuz its the cheapest problem to solve. i had this problem with mine and they had to be replaced.

Hey whats up, did yours make a vibration/sound also.I think I know how to test the u joints but how did you determine the problem?

it made really loud clunk upon sharp acceleration and then would vibrate while under power. i just knew it was either that or coupler and the coupler would be a lot harder fix and u-joints are cheap and easy to replace anyway. also on mine the drive shaft seal goin into the rear-end is cracked and leaks gear oil, so if yours leaks to either fix that too or feed it oil.

Thanks for the advice I am going to replace the u joints any way but at the end of the tranny should it be damp to wet with fluid I guess it is the packing seal leaking a little? Is that normal.

My 1980 K 20 4x4 is at the machine shop as I type this ,for the same thing your truck is doing ..i jacked up the back end and put the transfer case in low and the transmission in drive so as tohave the drive shaft turning slowly ..I couls see the drive shaft was turning in an oval pattern and when I held a stick ou to it the noise was intermitant as it only hit the stick once every reveloution ..In my case I need the drive shaft and yoke cut and re welded dead on ..it was welded up before in the bush and I never took it in till now to get it done properly.

Forgot to mention your leak at the back of the trans ..no this isnt proper ( maybe normal but not proper) this seal is not hard to replace ,but if you arnt showing any drips on the ground forget it ..just check trans level now and again ..what you need to do is wiegh the price of trans fluid against the cost of fixing it ..And be thankfull its not the front seal leaking