Bridger,
I made two of them a while back.
One w/ a red hull:
http://www.subsim.com/radioroom/showthread.php?t=122166
that you can download here:
http://files.filefront.com/U596+Medi.../fileinfo.html
and the same one w/ a grey hull:
http://files.filefront.com/Grey+Hull.../fileinfo.html
Neither has a black/brown mottled pattern, but from what I had read they used a shade of "Italian Blue".