I haven't seen a definitive answer about this and I have searched the forum. I bought a brand new in the box Shifter ZR4 setup but it is missing both the front heads. I also currently won a ZR3 setup for $99 on ebay.

Can I use the ZR3 front shifters with the ZR4 Interface and my Escort IX?
Is the firmware able to be updated with Shifter Tools?

Thanks everyone