The only problems I have with JC is their shipping charge policy which is based on the price of the unit not the weight. This is a particular problem when one or more parts of an order are back ordered. You wind up paying more in shipping than you would have if they had waited to ship a complete order. The other problem I had with JC was with door glass. The vent glass I got from them was a different shade of grey tint than the door glass placed on the same order. Also the door and back glass pieces had chips in the edges which would have been below the window sill or covered by the seal, but was not the quality I was hoping for. They took the pieces back and paid for my shipping back to them though. The door and back glass I got from Classic Parts was perfect. I do like JC's 5% off for internet orders though.
I have ordered from all the parts houses over the past four years and the only one I will not use again is Brothers just because their pricing is higher than any of the others.