Hi Roger,
The Merco engines or should I say, Rustler Merco are definately available from Ian Russell. They are I believe in stock, just contact Ian with a PM. As Brett says, The Rustler Meatamorph 40 is the one to buy, you won't regret it! It is possibly the best stunt 40 around. I believe there was suppossed to be a tie up with RSM at one stage (It was certainly a US company, but I can't remember for sure.), but for some reason the deal seems to have fallen through. Contact Ian direct, I can give you his email address if you prefer. But for obvious reasons I dare not write it here for fear of the spam bots!
Andrew.