Jerry,
If you haven't already, check out Caswell's new offering [link=http://www.caswellplating.com/models/]Caswell Models[/link]
Mike Caswell & Dave Merriman teamed up to market both static sub kits along with Dave's excellent line of D&E Miniature's Sub Driver WTCs, conversion kits & parts. Mike will be offering the revamped OTW line & has both the Seahund & X-Craft in stock. He'll have a full line of British & German subs to come that will offer a nice option to what is currently available on the market.
I'm getting their Gato kit for my Revell conversion & will probaby opt for one of the larger OTW kits later next year. Now that Lindberg announced their new 1/72 IJN series, I would presume they'll have some conversions coming for that as well.
Chuck