Hello everyone... I have seen a few 2 speed trannies for sale... but are these mainly for the diesel market?? Would it be possible to use a 2 speed on a blower motor to lower rpm's and extend engine life?..

Not a good idea to use it that way. Lugging the engine at lower rpm's is likely to cause high engine temps, oil temps, accelerated wear and detonation. Think of it as way overpropping a boat. Actually the best way to use a 2 speed trans is to increase rpms at low speeds to help a big cammed engine get through no wake areas and on plane easier.