then the D4D, yes that is a GPS, which is used mainly for spraying with a wheel tractor but when it is hard to see the mark seeding, we mount it on the cat, probably the only old cat to have a GPS in it.
now some of you who have seen ag cats working the northwest may know that radiator air scoops are used to keep abrasive dirt from the radiator. Nobody uses them close by because our soil is clay and not abrasive. Our D6C came with one on, we removed it and hung it up in the shed.