I’d consider it more cost effective to do it yourself if you already have all the parts. You need a torque wrench, a dial indicator, and some basic hand tools. I don’t consider the job overly complicated and hopefully that’s not just me.
Basic rundown of swithcing out ring gear carriers once the pumpkin is removed from the housing goes as follows. Mark or stamp the differential caps so that they get installed back on the same sides of the pumpkin. Measure your ring gear back lash at three different spots before removing the single track carrier unit from the pumpkin and make a note of these measurements. More than 0.003” variance between the readings and you’ll need to re-examine what you’ve got. On the posi carrier, insure you’re going back with the same size carrier side bearings as there are several. Deburr the ring gear side of the carrier and likewise the mating side of the ring gear with a honing stone before placing the ring gear on the carrier. Any burrs will have the ring gear not rotating true once it’s installed. Be sure everything is clean at this point. Put the ring gear on the posi section and torque the ring gear bolts down in steps to 65 lbs. Reinstall the ring gear carrier assembly back in the pumpkin and reset the backlash to the value you got with the original. The caps need to be very snug at this point but the spanner nuts need to be able to rotate freely within their threads. Recheck the backlash at the same three spots for the same measurements. Insure these measurements do not vary any more than 0.003” from the low to the high. Adjust the ring gear in or out to get the clearance values back to the original values. Don’t forget to preload the carrier bearings before you put a final torque on the carrier caps and install the adjuster locks. If the ring and pinion have timing marks, be sure those also align before putting the final tightening on everything. Before calling the job quits, roll the gears around with oil on them both forward and backwards and insure they are smooth and do not ‘rattle’ or have any binding spots.