This link is for the rear cylinders - the NAPA number is UP4511 which they say is the same as the raybestos WC4511
http://www.napaonline.com/NOLPPSE/(S...511_0246274790
This one is for the front - the NAPA number is UP4571 which they say is the same as the raybestos WC4571
http://www.napaonline.com/NOLPPSE/(S...571_0246274895
I could not find a listing for the correct style master cylinder for the C15A. The cylinder for the C15A has mounting studs on the base and has a 1-1/4 inch bore. I do not know of anyone who sells correct style replacement cylinders. They sometimes are available on eBay, but it is several months since I saw one for sale. As other people have said, the best thing you can do is get your old master cylinder lined with either stainless steel or brass.