FT-60E vs FT-60R TX coverage (446MHz) question

I'm a new owner of FT-60E but I'm in need of expanding TX coverage. In my country there's allwoed to use also 8 channels PMR (public mobile radio) on 446MHz. I know that FT-60 is designed to use on 2m and 70cm HAM bands, and does it well but there's a difference between 60E and 60R. On 60E TX coverage ends with 440Mhz so it excludes desired 446MHz. 60R TX coverage ends on 450MHz and it includes 446MHz. What makes a difference between these models? Is it a software limit or something general on PCB design?? I know there's a "MARS CAP" mod to remove one resistor from PCB board, and expand TX coverage to 470MHz, but this is not I really need. I need just 446MHz coverage that FT60R already has from factory.? Is there a way turn my Yaesu FT60E to FT60R? Richard ?

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