Sound Sales Trons were made between 1976 - 1980 and have a PML pre-amp card in them which combines the pre-amp cards for the volume and tone control.
They also use a different set of masters and have corrected some of the inconsistencies between notes, but in doing that the character of sounds are also changed.
For example, you can't play King Crimson's Trio and have it sound exactly like the original song because they corrected that loud high F, by reducing it.
Some of the sounds are more brash, like the strings. I believe it might have been done to compete with the buzzy brash string synthesizers from Elka and ARP at the time.
This was also done to some of the Mellotronics masters as well.
This partly accounts for the differences in Tron sounds from band to band depending on where they got their machines.
Some people who bought Sound Sales Trons prefer these changes but I'm not sure the tape formulation they used has the same physical quality. There might be a bit less grab to the tape, and that's vital for the tape to function properly.
If you want to hear Sound Sales Trons listen to American music made after 1976. Heart had a Sound Sales Tron for example.
There's others but I don't have a list handy. Hope this helps.