Hi I have a 98 blazer 4-door 4x4 with auto. trans. I just bought truck less than a month ago. It has 180,000 miles on truck,but new jasper crate engine only has 42,000. I've got a problem with the differential. I've had a bad vibration, ecspecially between 45- 70 mph. I thought that it was a wheel bearing or cv axle joint. But today I checked the front differential's fluid level, and I had to add * 1 1/2 Quarts of 80/90 Gear oil to fill up to plug. I think that maybe it has run low enough in oil for long enough that it has definatly done some damage. My question is what might be bad in diff. because of running low on oil for so long ? Is it best to try to repair mine or would I be better of with a used one out of a salvage yard ? Will it hurt to drive untill I replace or repair ? I noticed a big difference in low speed noise after I added oil , But I think the damage was done because It still vibrates like crazy between 60-70 mph.

 

You would likely be better with a used one. The front diff is difficult to setup properly.

 

I found one 3.42 for $ 200.00 out of a wrecked blazer. How do I know what gear ratio you have ? Do you think the right side extension tube or any of its components (ex. shaft,seal,bearings) could be bad because of running with no front diff. oil ?

I plan on replacing it this weekend. Guy said he could have it pulled same day from whenever I wanted it. Should I get the ex. tube shaft as well ? Im on a tight budget with all the money I've already spent on parts . Thanks, Chris

 

Check your glove box for RPO codes. GU6 is 3.42's