Discriminate MOS from BJT easily
Google the part number.  I just did, and while I didn't find a data sheet, I did find an NTE cross-reference (for an NPN).  This indicates that it's an obsolete consumer part.
Measure each leg against the others with the meter in diode mode.  


An NPN will show the base-emitter and base-collector junctions as one diode drop if the base is positive (and if it's a really old transistor you'll learn whether it's silicon or germanium).
A PNP will look like an NPN, only in reverse.
A typical MOSFET will look like an open-circuit from gate to either source or drain.  It may look like a diode drop from source to drain (for an N-channel) or from drain to source (for a P-channel) or it may be open, or (if it's depletion mode) it may look like a resistor.  If you really think it's a MOSFET you can try putting 10V or so on the suspected gate-source pins and see if the drain-source pins conduct.
A 3-terminal voltage regulator will just look odd