Tayda is out of the MPSA13s and I am not really interested in multi-vendoring this octarock build so, which two will equal the closest approximation if I roll my own darlington, 3904, 5088…..?
MPSA12 will work fine and Tayda has them in stock.
That transistor is an emitter follower output buffer, I suspect if you drop R47 (1M) down to around 510K you could use pretty much any single BJT with a similar pinout. (2N3904, 2N5088)
