Any way to identify "house numbered" parts? (not pedal related)

[somnif]

So, story time. (As a note, this has absolutely nothing to do with musical equipment, just me metaphorically banging my head against a circuit board)

My friend inherited a relatively obscure car recently, a 1980 Triumph TR8. Put a lot of time and fair bit of money into getting it back up to functional. And mechanically, its all there. But electronically... well late 70s England were not the best place for quality electronics. The ECU (brain) of the thing has a few issues. Since I'm the guy he knows with a decent soldering iron, he asked me to help him out. I reflowed a bunch of questionable joints, cleaned some contacts, the usual. And it worked for the while, but now we've run into a new issue.

Best guess we have is one of two things: the transistor powering the 5V supply has gone bad, or one/both of the darlington's powering the fuel injectors has/have gone bad. Managed to find a schematic of the thing, but annoyingly, the parts in question use non-standard parts numbers. And so, I have no idea how to figure out what a suitable replacement would be.

Does anyone know if there is a way to hunt down what these parts may have actually been? I dug up a 1978 RCA parts catalog, but lacking more info I'm not Entirely sure what acceptable replacement parts would be.

Q202 and Q204, labelled "RCA 17343", date code 15th week of 1979. TO-66 cased NPN Darlington transistors.


Q1, labelled "RCA 17344", date code 14th week of 1979, TO-66 cased PNP transistor.