EB, I installed an heng long tk6.1s mfu as it now has the servo recoil and elevation capabilities as standard that i needed for this build, I used 2 micro servos placed on the gun itself in the required positions which are small enough to be mostly concealed. The traverse motor unit is just a conventional one and placed under the floor inside the hull as normal. The new mfu also has 8 options for led simulation and one of these is for gun barrel flash, so I simply used a 5mm led / flash cable placed inside the barrel to achieve this, HTH
Cheers, Lee.