Oh, that was not clear, sorry.
You need to take two things into consideration:
1) The protocols are different between the rigs, as well as the controls. A hardware control "head"
would be quite difficult to get working across various brands and types. There is probably no ROI
to make the investment worthwhile.
2) There are not really any "heads" available separately on the market, with the exception of the K3.
The TS-480 kits are no longer being marketed and the RC-2000 is no longer available, at least in Europe.
73,
Mitch DJ0QN / K7DX