Differential repair or replacement?

The quote was $1600.00 for a repair using a rebuilt differential and $2200.00 if they rebuild mine. If they rebuild it I get a year warranty.

It only takes 3.5 hrs to remove and replace it not including this main part of the differential assy they gonna deal with see below and it only cost $350.00

Its a bad deal if it was me I'll make an about face and run like a speeding bullet and never ever see this guy again. Its your decision sorry this is all I got

First of all, if the pinion gear is missing a tooth then the ring gear is damaged and/or must be replaced. Ring and pinion gears are a set - you CANNOT interchange them. Even if the ring gear was ok (which I doubt) it must be changed. Damage to both pinion and spider gears indicates that pieces of debris were floating around in the rear. It will be more cost effective to replace the entire unit as compaired to repairing it. The only question is what is your price range -- a junk yard unit will have some miles on it -- call for prices. A new unit will run around $600.00- with zero miles on it and a warranty.
It is not smart or safe to drive this vehicle with a damaged pinion gear and spider gears. The rear WILL eventually sieze and explode. This could cause transmission - transfer case - and engine damage.

The $600 is just an estimate and is for just the parts required for a new rear (labor will be more). If you want to purchase the unit yourself you must know what the gear ratio is, what size the differential is, and how many splines there are on the axle. It is most likely an 8.5 inch rear but you should go to the drivetrain specialists web site. There you can see what is involved with identifying what rear you have. You can also purchase everything you need there. You must also decide what type of traction you want - limited slip or posi. If installing a new unit, I suggest going with a Trutrack with the new stock gear ratio ring -n- pinion and a timken bearing installation kit. If you do not know how to install this init I suggest having a professional do it. DTS has instructions, but if you don't know what you are doing you can easily mess it up. Once again, driving this blazer will lead to more damage.
BTW - be aware when purchasing a new ring -n- pinion gear set. There are different manufacturers. O.E.M. Is the quietest gear set and I suggest O.E.M. But if you are planning on going off roading and stuff like that then Richmond - U.S Strange - AAM gears are what you want. Motive Gears are junk.

Yes if the gear ratios are the same and they bolt up. Please let us know if you need anything else to get the problem fixed.

If you mean swapping the entire rear axle, as long as the ratio, ring gear size and the brakes are the same it should be OK. Be sure the 2 door isn't a ZR2 option as those are wider and use different mounts than the "common" versions.

If you mean just swapping the actual pinion itself, no. You would want to replace both the ring and pinion so they will wear in as a set.

Removing the rear shaft to prevent torque transfer to rear differential can work but the rear differential would still be turning when the rear wheels are turning. You cannot remove the rear differential as the shafts needs the differential bearings to hold them in position so the correct answer is no, except for moving the vehicle around for parking etc but not long distance or high speed drivings.

Ok as for the rear end working the wrecking yard has books to tell them that, I beleive it will work fine. Now what you need to know to make sure it will work is have the needed info. Now you need to know what rear end you have weather is is a 7.5 or a 7.62 and what gear ratio you have like is it a 3.73 or 4.10 or? If you don't know or don't have a tag on the rear end to give you the needed info then call your local GM dealer and give them the last 8 of the vin and they can tell you. As for driving it can't tell you I have no idea what it sounds like how loud it is and so on. Therefore I can't answer that question.

No and No. If you put an axle in place, there is no way to keep it from moving around in the (empty ) differential.

Based on what I believe you want to do, yes, the wheels will come off. There is nothing to hold the axles into the bearing.

Please be careful if you try something like this. I can't see how it could be safe.

Axle ID stamped on front of axle housing tube need to wire brush. Fist 3 digts are axle ratio next is axle assembly build last 3 are date manufactured.
Could be 7 5/8 or 8 5/8 ring gear