I just replaced the radiators in my street '99 Boxster. In looking around for replacement options, I found that I was either going to buy the $265 Behr radiators on Pelican Parts, $175 used radiators from a salvage yard or some $136 Silla radiators off of ebay.
I decided to go with the new Silla radiators and they were a perfect fit. I've only had them on for a week so I can't speak to longevity but the installation went perfectly. Since I couldn't find much info on radiator options before I purchased, I just thought I'd share.
Oh, the part number is 2288A for both left and right. You can find these elsewhere on the 'net but I got free shipping from the seller, autopartgear, and they actually showed up the next day.