I just got my 89 suburban 4x4 two weeks ago and now it is making a noise in the rearend.:neutral: It has a thump about 3 or 4 times when I take off, but not always. only does once and a while. I notice it more when i tow or gone up a steep hill.And more so when i take off easy. If I give it more gas on the take off it won't do it. It will do it backing and forwards. it also sound like it is coming from the left rear tire/wheel. It has new u-joints . I pulled the drive shaft out and greased it & slid it back in. I'm going to take the differential cover off and look at the gears , does anyone know what I should look for? I don't know if it is limited slip but could it be that? thanks for the help in advance.