[Racal] 6790 and 6790/GM ?????

[Lee Ritta]

Howdy Folks
I questions which I need answers to, I would like your help Please.
What is the difference between the 6790 and the 6790/GM. Is the 6790/GM
a later version. Why are the 6790 not as common? What boards are different?

Does anyone have any spare audio output transformers as used on the A4
board? Does anyone know a replacement for the ua757 ic, it is U8 on the A4
board.
I will look forward to your answers.
73 Lee VK5ZNA