Rik's is the best and most responsive.  They usually have most everything in their catalog and they are a husband/wife small business.  They ship fast, keep you informed and out perform all of the big guys.

A chance for me to plug my favorite parts people always go out of their way to help you out and what a great selection of used parts along with new not to mention the discount for C3VR members.                                                          

I'll second the Bair's plug!  I just ordered a quartz clock conversion and a shifter rebuild kit.  They usually ship next day and their prices are very competitive.  (Shifter kit was $53 compared to $80 or $90 from some of the big outfits).  They also have good, personalized communication regarding when they are shipping and other info.