I have never worked on a TD-742.
I believe they are rated at 60 watts into 4 ohms.
Now the TD-752 I Have worked on.
Rated at 100 watts into 4 ohms.
The 752 uses J50 & K135 mosfets for the outputs
Not too sure what BK Butler used for the outputs in the 742.
Here is the 752 schematic.
Maybe it will be of use.