Hi there,the SJ prefix tells us that it is a Motorola device,I would try to get the orig.'s if possible.A sub from ECG,(now NTE) would be a NTE - 219 PNP,Si,audio amp or switch use.It's mate would be a NTE - 130 NPN. The Motorola's are a better trans.,in my opinion,if it was my amp,I would try to get the originals,or replace them all with the same make.Good luck,Mel.