For at least 25 years (if that is correct), no new devices (not NTE/ECG) in the TO-66 package have been introduced - the closest equivalent to the TO-66 package is the popular TO-220 package in terms of dissipation.
I am not sure about this, but new devices in the TO-3 package have not been introduced for at least 10 years - the closest equivalent to the TO-3 package is the TO-264 or TO-3P (not the TOP-3) in terms of dissipation (the TO-3 package MJ11032 can dissipate up to 300W and the TO-264 MJL21193 can dissipate up to 200W).
I am not sure about this, but new devices in the TO-3 package have not been introduced for at least 10 years - the closest equivalent to the TO-3 package is the TO-264 or TO-3P (not the TOP-3) in terms of dissipation (the TO-3 package MJ11032 can dissipate up to 300W and the TO-264 MJL21193 can dissipate up to 200W).