Tait use 3 digits to indicate the basic RF configuration of the radio.

The first digit in the RF Type group designates frequency band.
T2020-(x)xx

'1' for 220 to 270MHz
'2' for 66 to 88MHz
'3' for 136 to 174MHz
'4' for 175 to 225MHz
'5' for 400 to 470MHz
'6' for 450 to 520MHz
'7' for 330 to 360MHz
'8' for 800 to 870MHz transmit  851 to 870MHz receive
'9' for 360 to 400MHz
'0' for 500 to 530MHz

The second digit in the RF Type group designates radio IF bandwidth.
T2020-x(x)x-xxx       '1' for wide band (15kHz)
                      '2' for narrow band (7.5kHz)
                      '3' for medium band (12.5kHz)

The third digit in the RF Type group designates frequency stability.
T2020-xx(x)-xxx
Options
T20XX-XXX-XXX The third group of digits covers a wide range of software and
market specific options. The large number of options and their frequent
changes precludes listing them here.

Hope this helps a little
mike g7bnf