Hi all. I have a set of old TO-3 transistors pulled from an old HarmanKardon stereo unit. They are labeled SDT-9261 and - what I assume is the date code of 6741. Best I can tell from my measurements, these appear to be NPN with gain ranging from 7 - 17. The HK unit was a low power receiver/turntable combo unit. The manufacturer marking is a capital "S" in a vertical rectangle (STMicroelectronics maybe??) There are also 2 other TO-3's that are fairly pitted on the outside and are hard to read, but I think they are labeled 86 5043 2, then below that VFS2745K. No manufacturer marking is apparent. Any ideas? Thanks.