There's no BCxxx transistor starting with two digit number, so it might be a BC174 (but these don't have the -40 suffix, rather A/B/C), so it isn't the BC174, same with the BC274, then we have a BC373-40 (but no BC374), no BC474, no BC574, 674, 774, 874
There's a BCX74-40 made by Siemens, I guess this one is right, since there's some kind of X top left. Normally transistors of this vintage are marked with the full type number, just a bit scrambled

So its data: NPN, 45V Uceo, 800mA, 625mW,
-40 indicates beta in the ballpark of 400.
BCX types are usually fast switching bipolar transistors.
http://www.rsp-italy.it/Electronics/Databooks/Siemens/_contents/Siemens%20Transistors%201980-1981.pdf