You definitely want Rams like everyone has stated.
Otherwise you could take one of three other options.
1. Red Paint. This will you let you move an extra 1" which sometimes can make a difference. Not everytime, but at least know when your Trukk gets blown up, you'll be 1" closer to the enemy.
2. StikkBomb Chukka. Never used them myself, but if you happedn to be facing an enemy with low initiative and there is a lot of cover, it could possibley help you assault at your own I3 or I4. This is of course, if your Trukk lives long enough to see an assault.
3. Extra Big Shoota! You already have one, but it never hurts to have 2. Getting an extra 3 Str 6 shots is always nice, even at BS 2.
Just remember, whatever you do, Take Ramms. and only one other 5 pt. upgrade!!