Still sad to see those puppies go; my old one might actually be on Canadian soil now (National Service 92/3).
IIRC they're all Batch 4 vehicles. As to the different shades of green, replacement parts always seemed to look much greener (olive-green vs. olive-drab, more or less) than what was already on the tank, and no two tanks looked the same, even in shade of original OD.