Rear end clunk

[85silverado031490]

Hey guys, i have an 85 c10 lwb and the previous owner had a 4" drive shaft custom built for the truck because i guess he thought it was necessary, any ways when im putting it from park to reverse or drive or neutral i always get a pop or clunk from the rear end no matter what, and when downshifting from 3rd to 2nd or 2nd 1st i have a small one as well; the pinion yoke will move side to side and up and down a small amount do i know that the bearing preload is not correct or completely nonexistent and that that would cause the gear mesh to be incorrect. My question is should i just replace the inner and outer pinion bearings and reset the crush sleeve and preload or go through the whole rear axle? Keep in mind that i am planning to switch out the stock le9 305 motor and install a mild 350 in place. I feel like the huge rotating mass of the heavy drive shaft is what killed the bearings in it, and i believe its the standard rear axle which is a 3.08 and i would like to switch the gears to a 3.73 or something a little smaller than that. If anyone has any insight as to this please let me know cause its driving me absolutely insane.  J.S.

[Powerdriver1958]

1st the step From 3:08 to 3:73 is a big one . 3:73 gears seem to leave me with a cruise rpm of 2,500 to 2,700 . Not fuel mileage friendly .

On 2 different trucks I found the spider and side gears to have a lot of wear and that was the cause . If you have any drive line problems at all that's where I would start ( 1st cheapest is generally where I start )

[85silverado031490]

Ok I got ya on that, I guess the best thing to do is open up the rear axle and look at what I may or may not still have , ugh, heres a second one . Drivers side lower ball joint is spinning inside the control arm when I turn the wheel, ok so I was gonna buy new oem replacement arms from like dorman or somebody,  nope , the only options I see are on summit racing and they are all lower arms with a 3 inch drop for use with the stock coils, I have 32 by 11.50 by 15 inch tires coming this week for this truck and I am not gonna give up my tires because of this,so what in the world am I supposed to do? I know moot offers some specific ball joints that are a few thousands bigger as an option but I don't know if there are any for my application. Or should I just replace the lowers with moogs And see if they go bad again?

[Powerdriver1958]

Salvage yard is next or it would be for me . I wouldn't take a chance on the control arm . Replace it , stuff a new ball joint in the salvage yard one .

[bd]

1985 C10 ... Drivers side lower ball joint is spinning inside the control arm when I turn the wheel, ok so I was gonna buy new oem replacement arms from like dorman or somebody,  nope , the only options I see are on summit racing and they are all lower arms with a 3 inch drop for use with the stock coils, I have 32 by 11.50 by 15 inch tires coming this week for this truck and I am not gonna give up my tires because of this,so what in the world am I supposed to do? I know moot offers some specific ball joints that are a few thousands bigger as an option but I don't know if there are any for my application. Or should I just replace the lowers with moogs And see if they go bad again?

Napa - complete left lower control arm

[Fairlane514]

The way you describe your rear end, it should be whining a lot.....is it?