Note those are not the same, one is PNP, the other NPN. They form a very basic push pull drive stage. They would have the same specs each though, other than polarity.
I don;t know what the originals were, the numbers like 37150 look like Fender part numbers. I'd look them up in an old fender parts book, but all mine are stashed in the warehouse somewhere.
SO what package are they? TO92? TO220? TO39? SOmething else?
What voltage is the main supply? The drawing says all caps 50v, so I assume the circuit runs on something like 25-30? So these transistors need a voltage rating of something higher than that. I'd have to say I bet 1 amp is enough current rating.
Education is what you're left with after you have forgotten what you have learned.
I'm sure BC639/640 will fill the bill; problem is that European transistors are not that popular in USA; maybe somebody can find some commercial widely available equivalent. I hate all that unnecessarily expensive NTE deal.
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