Glen,
  I 
  would concur with Frank concerning placing the pistons on the outside (believe 
  they are nitrogen-filled), corrosion and the elements will mess them up 
  quick…this is why they put them inside of the car.  Another issue for you 
  to consider as Frank eludes to is that anything placed in the sail will just 
  make things tighter on entry and exit, especially if you need to make an 
  emergency exit.  You don’t want to snag on anything while trying to get 
  out of a flooded sub.  Simple is always better.
  R/Jay
   
   
  Resepectfully,
  Jay 
  K. Jeffries
  Andros Is., 
Bahamas
   
  Save the 
  whales, collect the whole set.
   
   
   
   
  
   
  
  Hi 
  Glen. No, I haven't cut the holes in the bottom of my 
MBT's.
 
  
  Once 
  all the welding is done, I'll pressure test them using the air input/output 
  fitting with a "T" and a gage.
 
  
  If 
  the pressure holds for 24 hours there's no leaks. If it leaks I'll spray soapy 
  water on the welds and find the holes. Drill them out and re-weld. 
  
 
  
  I 
  have no battery pods. The batteries ( 14 ) are inside down low and each set of 
  3 is inside a stainless 12 gage box with a gasket and lid. Rubber grommets 
  where the cables exit. Not really water "proof" but pretty much sealed up. To 
  charge them, I'll open the lids and have a fan sucking the air out of the sub 
  to dissipate any gas build-up. 
 
  
  On 
  the gas shocks, I would consider putting them inside. Anything outside gets 
  salt water and pressure applied, increasing maint enance. If a device needs to 
  be outside , well OK, but if it can be avoided it seems logical to put it 
  inside.
 
  
  I 
  prefer exterior springs because it keeps the hatch opening clear but you may 
  be able to mount them at the perimeter of the flange inside so they don't take 
  up much room.
 
  
  The 
  thing is ( to me ) that anything outside requires extra measures to protect it 
  from pressure, collision, and corrosion. If it can possibly be located inside, 
  it's subject to only the one atmosphere of the cabin, doesn't get wet ( well 
  maybe a little ) and can be reached while submerged if it develops a 
  problem.
 
  
  I'll 
  be carrying some extra scuba tanks outside but the main air tanks will be 
  inside.
 
  
  The 
  only things outside are the 4 motors, 4 actuators for rudder and dive planes, 
  and whatever lights I add later. For now I have a location molded into the 
  side dive planes for mounting two battery operated dive lights ( like flash 
  lights ) and they will be switched on before each dive. No thru-hulls or 
  wires, just replace the Duracells when the batteries get old. They won't be 
  real bright so I will be adding some serious lights later with thru-hulls and 
  wiring. I will be adding a video "periscope" to the hatch but again, it will 
  be contained in a housing that connects to the main cabin. Dry and one 
  atmosphere. If it springs a leak I'll pull the wires and close the valve 
  leading to the camera housing.
 
  
  I'll 
  keep a Hi-Res video camera inside to shoot video through the windows, so the 
  rotating "periscope" camera will be for looking forward and around with the 
  image on a small screen just above the two upper windows.