Nothing but good luck with them. Worth your time to compare prices though. Sometimes on the cheap side, sometimes really high...
I've bought a couple of things from them and it worked out well. No long-term experience with them, though.
I've bought off and on from them. Sometimes they have really good prices, sometimes not so much. Seems about the same quality as our local parts place...
I use them all the time. I needed a clutch kit for My FE project. They had several options and prices. I rolled the dice on one of their manufacturers close out specials. (no name mentioned) When it arrived it turned out to be a Borg Warner Brute for less than 90 bucks including shipping.
All the local Napa, Carquest etc, said I had to buy the complete Gates overhaul kit for a P/S box, but I knew the 2 small seal kits were available from Gates. Yes, Rock Auto had them in Gates brand, and even with shipping it was 1/2 price of a OH kit.
Bought a voltage regulator from them for my 60 LeSabre, showed up early, looks exactly the same as the old one, worked fine till my generator went tits up. Gotta fix that. I'll buy from them again!
I have used them several time. I have had good luck. There prices are pretty good, but check locally, sometimes I had found with shipping it can be higher. But good products and company. They even emailed me a discount coupon to use the next time.
I love rockauto-- their prices are consistently about the best, and the catalog they use allows you to cross reference all kinds of parts- love it.
I've used them a few times and always got what I ordered in a timely manner. However, I hate the fact that they charge shipping by the number of parts you order and not the weight. i.e. If you order 4 flywheel bolts, you are charged 4 shipping costs, not 1. The shipping is what killed an order for me.
Nothing but good things to say about them, with the exception they offer a credit voucher and expire it out so quick I could never seem to ever get to use them.
Just so you know; at NAPA, the kits and individual parts are available in MicroTest; for most any application you can think of.