Thanks for that - so it seems that for me the Benedini card is the way to go. The IBU3 look a top notch board but the price is a more than the Clark and TBS mini together (and then some) and having already got the Clark TK22 on this tank it makes sense for me to go this with the M36 at least (I am considering a IBU for my KT project however). I have read a lot of good things about the Benedini and they can apparently add more functionality as well as great engine sounds?
Yes, I think a speaker box around that size should fit fine, depending on what you decide to do regarding the turret motor/drive set up. Forward of the turret you do, as you point out, have more space simply because the hull is just a Sherman M4A3 (which Mato already have in their line up, and hence why they supply these M36B1's whith a wrongly place barrel lock).
There is also some clearance between the top of the gearboxes and the hull roof, not a lot, but enough for locating the main switch under the drivers hatch if you want to (I will be doing this at some point - Mato just leave the switch flopping around in the hull. The hull tub itself is small but it does have the advantage of more usauble space on the side rails because of the relatively tall design of the Sherman hull in this respect. Bottom line is I don't think you will have too much difficulty in doing what you suggest at all.
