You can get most of the transistors from bdent.com. The 3675 is end of life but you should have no issues tracking some down. Plenty of alternatives too and if you are in a bind, PM me as I have a few hundred. Ditto on the 1486 and 1968.
The 1156 should be replaced with the 1486 if you are using that one in the PSU.
The RLED is actually the chassis led indicator and has nothing to do with the circuit. Just pick a LED and feed the forward voltage and desired current through an online calculator. It's fed off the +15V supply.