Yes, both. Not too many long ones out there. The short has the Simul/Class A switch on the back of the chassis, the long on the front panel by the standby and power.
Lots of info on MkIII ...do a search, grab a drink, sit back, and read
But to answer your question, those marked "SimulClass" are designed to run EL34 outer pair and 6L6 inner pair, though some have placed 6L6s in the outer pair for tonal reasons. Then there is the 60watt and 100watt versions which are designed to run a single pair or two pairs of 6L6s.