Electronic parts without datasheet? Answered

Taking parts off electronic junk collected over time: Now ready to demolish a huge LCD TV (matsui) with the power supply circuit board missing (origin: dumpster).  Quite some mean looking 'transistors' on large heatsinks. Before turning the heat gun on it, I tried to look up the serial numbers on them, but found nothing. Does this happen often?
If not found, is there a way to measure, or otherwise find out what the components can do?

(I still have a steep learning curve ahead, right now I mostly want to know if it's worth the trouble stripping them off)

The LCD/ backlight part: Is there anything this can be used for (without working control electronics)?