I've got an IRd 7-speed I picked up from rivbike and it was pricey, but it's very smooth with little clatter going up or down. Here's an eBay option. The seller is in Portugal, but he's a very nice guy and seems to have an unlimited source of NOS vintage DA stuff; this is just one of several freewheels and cassettes he's got on auction at the moment.

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT