I'm working on an EF Johnson 1200 series 440 MHz repeater.
One of the transistors in the transmitter is fried, and I have had
no luck finding a replacement. Can anyone help with a cross
reference?

the Johnson part number is 576-0004-055

Its a white, ceramic case with the 4 wide leads. Many RF power
transistors of this type have a stud to attach it to a heatsink.
This one does not.

It has the Motorola symbol, but only the Johnson part number.
I've looked though Motorola data books and cannot even find
this package style.

Steve