8 3/4 bearing job advice

[Dmichels]

Got a 8 3/4 4.10 cone clutch. I think I have a bad pinion bearing. I understand how to do the job and retain the original bearing adjustments. I plan on using a solid spacer to replace the crush sleeve. I do not think I have any gear problems. Should I just replace the bearings and be done with it? Will a new bearing affect gear contact if set up like the old bearing? Should I check gear contact? Is it a bad idea to mess with a set of gears that ran together for years? I imagine bearings are of very high precision and should be 100% interchangeable without readjustment
Thanks
Dave

[A383Wing]

with new bearings and races, you will need to set pinion depth and gear backlash per service manual

[moparnation74]

8 3/4" 3rd member bearings.

741 case
Differential 57-early 69: 25590/25520
Differential Late 69-74: LM104949/LM104912
Pinion inner: HM89446/HM89410
Pinion outer:M88048/M88010
Seal: 8515N

742 case
Differential : 25590/25520
Pinion inner: HM803149/HM803110
Pinion outer: HM89443/HM89410
Seal: 7216

489 case
Differential: LM104949/LM104912
Pinion inner: M804049/M804010
Pinion outer: M88048/M88010
Seal: 5126

[Dmichels]

Thanks for the info I guess the original shims and back lash adjustment would be a good place to start. Should I try to get the new adjustment to match the old wear pattern or should I treat them like a new set of gears?

[moparnation74]

I would treat it as a new set.

[justcruisin]

While you have it down it would pay to split the center section and inspect the cones, especially if it is a high mileage unit or it has had a hard time.

[John_Kunkel]

A bearing change shouldn't affect the pinion depth, lots of folks have use a bored-out rear bearing to ease shim selection.

The cone-type Sure-Grip can be tested without disassembling, two axles and a torque wrench will do.

[fy469rtse]

I agree with John, 
Straight forward, just pays to check gear mesh adjustment,
Gear mesh paint and check the pattern , FSM good reference guide for this
Good upgrade to get rid of the crush sleeve, only weak point in a good pig assembly
You shouldn't have a problem with pinion depth if you put the shims back as installed,
Good chance to up grade to the better trac lock centre if the cone type sure grip worn out ,
The trickiest part for me when learning on these was the inch pound setting on pinion,
Read the factory manual a couple of times and it will make sense

[Dmichels]

Thanks for all the input. I already have my beam type inch-pound torque wrench.
Dave

[justcruisin]

I agree with John that the center section can be tested without pulling it down, however it does not give you an indication of the life left before the cones bottom out.