Difference color makes -1958

[colorfixer]

It probably wasn't until the advent of AM stereo that many, ok most, had a decent studio and studio to transmitter link with decent bandwidth, around 8-10kHz. In the early days, where studios were linked to their transmitters with leased phone lines, the runs were likely through one office, or direct. This meant that the bandwidth was greater than 3100 or 5kHz.

Almost every AM tuner made today, other than say a communications receiver, has a set of IF filters that are way too narrow than what they have to be.

So, if the simulcast was done in the 50's with small market station that had a metallic pair from the TV station and from the radio studios to the transmitter it was probably better than a lot of people were used to.