same hull and tower, the difference is that the one based on the typ 18 has six tubes like the real Jyunsen B, the other one based on the typ 9 has two aft and only four tubes front, which makes it more of a Kaidai type sub. When you start a campaign, penang only, you should see Jyunsen type A modified (typ 9) and Jyunsen B (typ 18) as the possible subs. the former should work ok, the latter has a tower emplacement problem. Neither has any tube doors yet as I can't seem to find any good data, here is the only pic I found so far :
@ Takao : did you manage to scan the picts of the I 9 ? otherwise if you have a digital camera take a (few) pic of it (high res please) and put it up for download, I'm also interrested in details topside.