Here are a couple of kit bashed steam tanks.
Both are on the same chassis. This started life as a Crusader kit from Airfix. The rear ramp is from a 1/87 scale Minitanks M113, as was the large rectangular hatch. Embar provided the tracks from their 1/72nd scale Whippet http://www.wonderlandmodels.com/products/emhar-172-mka-whippet-ww1-tank/. I took the right and left tracks and sanded them so they formed a single track unit that could be either the left or the right (making the casting so much easier). The front turret is from a Battlefront Humber Armored Car, with the 15mm BESA replaced with a Stan Johansen Maxim gun. The two versions shown are a rocket armed version and a gun armed version.
The gun turrets in the rear of these vehicle are from Gaming Models http://www.gamodls.com/ in particular these guys http://www.gamodls.com/Nations/British/A-9_3.JPG. The A-9 turrets are nicely rivetted up making them perfect for steampunk. The kits from Gaming Models are really nice. He produces a number of vehicles that no one else makes and his prices are about half of what everyone else charges.
Here is a rocket amred version. In scale these would be 6 inch rockets. Each packa has 12 rockets so it will bring 24 rockets into battle and two full sets of reloads. The rocket packs are from Rebel Miniatures http://www.rebelminis.com/, specifically these guys http://ep.yimg.com/ca/I/yhst-51356505839231_2196_43616698 which are Tempest Grav Tanks.