.... the JEDEC registered device 2N2907 (and the NPN complement 2N2222) called out the metal can case defined as TO-18, and 400mw. (Transistor Outline xx). This is way back in the days (late 1960's) where all transistors were in hermetic sealed metal packages, long before it was understood how to encapsulate in plastic and get the heat out (low thermal resistance junction to case) w/o cracking the die, moisture resistance, etc. Advances in lead-frame, die attach, die shrink, and plastic technologies made plastic die encapsulation feasible. PNxxxx (P=Plastic), or MPSxxxx (originally stood for Motorola Plastic Semiconductor, which is now ON semiconductor). The plastic case is defined as JEDEC TO-92 (or the European IEC defined SOT-54) Most manufacturers have pruned metal can devices for die free package cost reasons, even the Chinese manufacturers. Some manufacturers do not spec ft, gain bandwidth product, but this is usually not an issue for GP applications. Power can be spec'd anywhere from 400-600mw, depending on manufacturer, die size, leadframe, package, etc.
FAIAP, in 98% of applications, a 2907 is a 2907 ......
Don't get me started on the SMD versions ......
