Note the extra armor, the shield around the drivers vision port and the use of sentinel legs for the flamer barrels.
Note the superb eagle and scroll on the side of the turret and the use of the gun shields to tie in the autocannons.
Check out the drums of ammo on the heavy bolter sponsons, double track construction and the upside down dozer blades for mud guards.
I hope some of you have found something in these three pictures to try on your own. I know ill be working on some heavy bolters with those drum magazines.
Here is a link to my idea gallery where you can see more Inspirational conversions.