This has been gone for a long time, but here are some pics of some of the mods I did on a $15 rustbucket New Braunfels offset.
I removed the firebox and added a baffle/heat diverter that covered a good portion of the opening and directed the heat under the cook grates.
Applied a length of Rutland rope stove gasket between the f/box and cook tube, used high temp Permatex silicone to make a gasket on the cook tube door-it was actually pretty tight!
Extended the exhaust vent with a piece of flashing down to the cook grate level.
12"x12" perf steel charcoal basket
4 wheel drive!
Sold it for $125