What current production decoder will fit in the Spectrum 0-6-0?
A real good place to get your answer is at Tony’s Train Exchange. You tell them what you have, and they will tell you what you will need. I had one HO scale engine in which they said to install a N scale decoder because the draw was so small! I’m not advertising for them, I just had good results from them. This is their new website address: http://tonystrains.com/
I suggest a Digitrax DZ123, DZ143 or TCS M-1, get them from Tony’s. Also, make sure to remove any EMI suppression capacitor(s) and resistor(s).