Hi Rik,

Welcome to our addiction!

PM blitzkrieg65 for El-Mod questions (he's the US dealer for El-Mod and a really helpfull guy).
His website (www.rctankwars.com) recommends the Futaba 7C (next model up from the 6EX) for guaranteed El-Mod compatbility.

If you want to keep the smoker, then you might want to consider his RC2HL kit, which interfaces between a regular receiver module and the HL motor control board (and also adds a bunch of other stuff like IR combat capability)
Its still limited to the performance of the HL board (ie 5 speeds rather than fully proportional), but its alot cheaper than El-Mod if you want to go all out and have the sounds and IR capability.
The Futaba 6EX would be fine with that system, you may even get away with the Spektrum DX5e (which is much cheaper, at least here in the US) - but I haven't tested that as yet.

Martin

PS. a friendly word of advice: posting Ebay links upsets the mods here...