Quoted from KenH:

If you compare the two datasheets:
http://www.nteinc.com/specs/10to99/pdf/nte54.pdf
http://www.mouser.com/ds/2/308/MJE15028-D-110804.pdf
They have similar max ratings and electrical characteristics. I think the NTE one would be ok, but I couldn't find a datasheet for ECG171, so not sure on that one.
MJE340/350 also will replace these transistors, are cheaper by 1/3, and can be installed standing up, rather that cross-legged (may depend on your board).
https://greatplainselectronics.com/products.asp?cat=103
Be aware that any replacements may have different pin arrangements than the originals, so make sure you install them correctly. Sometimes you have to line up the legs differently to fit the right holes. For further confusion, the boards are not all the same, some had holes arranged differently, and some had holes for two types of transistors. Best thing to do is get the schematic, and label the BCE holes on your board accordingly, then figure out the best way to line up your replacement transistor legs. You may be able to stand the transistors up, or may need to cross legs to get them in the right holes.