I would also like to know the same for my 7420.

 Dealer said that they can not connect it because they are not labeled as such.

 He did not say it would not work.

 There is a 3 wire plug in harness in lower rear  right corner of cab behind seat that goes up to the switch on joy stick harness. I think all that would need to be done is attach in to the shifter switch harness up on console. That is how it is supplied on my 7230. If I had the correct connectors I would have made one all ready to try it.