[Pyrotechnic]

Look on the glove box and see if there is a gear ratio listed. If not, you will need to pull the rear diff cover and count teeth. Teeth on ring gear divided by teeth on pinion is your gear ratio.

Depending what happened to your rear end will decide how much it will cost to fix. From there you can add a posi or whatever else you'd like. See how far gone it is, sometimes a rebuild comes out better than a junkyard axle and you are starting with fresh parts.

The other option is to grab a junkyard axle with the same ratio. Pull the cover, make sure it's looks good and hope for the best.