I found some sickle bar mowers on-line. First I found one in a 2003 John Deere brochure, but can't find it on their web site. Here is what I found:
http://www.wikco.com/befsbm.html
http://befco.com/products/hayequipment/sicklebar.html
http://www.ssbtractor.com/page3.html

These are just a few I found using Google. Also, farm auctions occasionally have some. I need to look into getting one for myself. I'd hate to sink my JD 4020!

Shawn