Thanks for all of your replies...yeah, it was leaking back when it was extremely cold a few weeks ago and the temperature has moderated since then. Maybe the seam expanded enough to close up for now.
BTW - I found the all brass radiator on ebay:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7951122190
I contacted a buyer who recently bought one for a M107 body and was very happy with his so I took the plunge. The seller sells several different models for different body styles. I haven't installed it yet but it came shipped in a bullet proof box and the price was quite fair. It looks like a good unit and is all brass. If anyone is intertested I can post a follow up and let you know my impressions of it after its in.