I saw these 1st generation big block Cougars on eBay. One is a four speed.
Steven
390 4 Speed
http://cgi.ebay.com/ebaymotors/?cmd=ViewItem&item=261034041129&redirect=mobile
XR-7 390
http://cgi.ebay.com/ebaymotors/?cmd=ViewItem&item=251072674924&redirect=mobile#ht_500wt_948