They don't usually let you take pictures of the boat inside. Must be new rules which is nice ;]
The TDC is in the conning tower, off limits.
Its a type IXC for clarification.
HA! When I went they gave me and my bud a free private tour at the end of the day.
I will be back in Chicago May 21 to 24 ;]
Also, don't want to burst the your bubble but, its gonna be a 2.5 hour tour of the exhibit and the boat, meaning you wont be on the boat for the whole time. The exhibit itself is huge so It will take 2 hours to walk you through all that and maybe give ya 30 mins on the boat.
Where did you read they let you take pictures of the boat inside?
http://www.msichicago.org/whats-here/tours/u-505-bts/
Couldn't find any mention of that. They told us they would not allow photography because they feared we would sell or use the pics to make money some how lol.