If you want to get to the M110E5 Heavy, you have to follow the T1 Heavy line. I've got the M103 and it's pretty much stock. Seems it doesn't start performing until you get all the upgrades on it. Trouble with tier 8, 9 and 10 tanks, etc., is coin, unless you've got a premium account. Ten bad matches and you run out of coin, fast, so I don't play mine, much.