i think i am. generally i do all my own work, but being busy and not a expert led me to take my '93 manual w/ chrysler 8.25 to a local shop with noise in the rear diff. i had diagnosed the trouble as a pinion bearing which they confirmed. i paid them $669 to replace carrier bearings, pinion bearings and seals, as well as axle bearings and seals. i thought it was a bit high, but i am a bit expensive as an arborist, so fair enough. 3 months/ 3k miles later noises from the rear. i drop it off with them. they are claiming that the spider gear is coming apart and that it needs to be completely regeared. the owners claim is that this problem is unrelated to the work his guy did, and wants $1000 for the work. help me understand guys, please.