linomaniac

if you asking me, answer is no

i think that 01xx is for 5C0 035 680 MIB1 devices
02xx and onwards is for MIB2 devices (some say that 04xx is MIB3?) but i think all devices with letter index are MIB2

firmware series are not intrechangeable, on my B unit i cannot upgrade to x3 and 04, my original was 0245 and updated to 0253

5C0 035 680 MIB1 01xx fw
5C0 035 680B or C MIB2 02xx fw
5C0 035 680 D-E MIB2,5 03xx fw
5C0 035 680 F-G MIB3 04xx fw

i don't know if it is true, i just found this explanation somewhere in the past

alpha index explains also equipment of the unit, if it has DAB radio or something...

i lost the link