CTC-4 with an FJP?

[stromberg6]

I don't know why exactly the mods aren't indicated for the AX, but it may have something to do with the type of demodulator. The 4 used high level demod, while subsequent chassis used low level that required the use of -Y amplification, with the notable exception of the CTC-5 "Special" chassis. Real "special" lol. Maybe someone can provide a better explanation for the lack of circuit mods for the conversion from AX to FB.
Kevin