I think that box is the one that should sit infront of the gunner, as that box has the rebate for the push rod to move under it, does it still have the lid ? get it shot blasted and saved ! John Bizal charges circa 250 bucks for one of those (repro)
glad you got her home mate well done !
Richie
I could have sworn this was a mk1

it has the tank breathers on ala Mk1 and the gauge cluster looks mk1 however the gunners seat is mk2, the battery position is mk2.... i am still think its a Mk1 though

if the number on the side is original it deffinately is. The tank breathers mounted onto the side hull was a Mk1 only design (so i am told)..... like anything, stuff gets moved around and if broken it is superseaded by later available parts.... for instance mine is certainly an early Mk1 but has Mk2 seat back brackets.
As for the engine stuff 99% of the bits can be obtained no probs and not expensive either, you need to know what flathead you have, check for data plates, also by counting the head studs lets us know if it was a "Biggun" or a "Lillun" hehehehe