Hello Lee. The conning tower on both the Type 7C and D should be the same . This was a 7C with a 9.8 meter section added aft of the control room . The cut was made at frame 39 , since this was an elongated 7C the designers did not even change all the frame numbers on the ship construction drawings !!! the added section is only numbered frame 39A to 39N . I have much experiance with this boat , I have studied it for years and now have an 8 foot long 1/32nd scale R/C model ( not yet ready for the water ) I have some very good drawings showing the cross sections , if you would like a copy please let me know . Also the keel is wider in this area than the rest of the boat due to the fact that the mine shafts were almost as wide as the width of the keel , at frame 39 -1700 , before and after this frame it is -1100 and farther fore and aft the width decreases slightly as in all type 7's .