I know the discussion has been around for awhile to have a Commonwealth Tech Tree and this has pretty much been shot down, well what about expanding the existing tree's to include unique tank designs from small countries.
Lets start with the British Tech Tree. From the Centurion I, have it branch in 3:
1. The existing 7/1 line;
2. The SADF Oliphant Mk1A; and
3. The IDF Sho't
The interesting thing with the Oliphant is the South African's utilised modified M46 engines in the Centurian hulls.
This raises the possibility of researching certain packages in one nations Tech Tree which ultimately unlocks packages in another nations Tech Tree.
Here's some info on the Oliphant Mk1 & 2.
http://www.tanks-enc...lifant_MkI.php