They are cheap enough you can go direct on 'em:
http://www.roushparts.com/detail.asp...ID=RE03-1000-A
When you order confirm this is the 351W part number, I don't have their catalog on hand but they make 2 versions of this.
The GM 1 wire can come right off eBay:
http://cgi.ebay.com/ebaymotors/ws/eB...sPageName=WDVW
Or if you want Powermaster has the best quality I have seen for a little more $$$.