a buddy of mine recently got quoted for a gear install and a posi rebuilt for $350. this price includes everything but the gears which he is supplying. it was $225 for just a gear install but since he's got well over 90k on his '99, the dude at the gear shop suggested they rebuild the posi.
It sounds like it's in bounds. I paid about $800 for a 3:73 upgrade.Gears, extra trac-loc clutches,speed cal.And they(the performance shop) did a shiit job--I went to the dealer a year later and re-did everything. The $350 is a good price..if they do it right the first time.