Yes it is possible. I did our 2002 STX but I had the nav controller and antenna to swap into it from the combine.I also added the ISOBUS harness to control a flexicoil bin with the one monitor (pro600)
It was likely cheaper to go with a trimble system but it come up good and I wasn't selling to tractor anytime soon
I would say go with Trimble. U can run rangepoint FTx for $200 a year. With outback (I have both), u are stuck with waas. As well if u buy from a case dealer they will know how to get it setup for ur tractor. I run omnistar in my quadtrac and it is awesome. $800 per year is cheap when u consider 0 overlaps. Just 10" rows across the field.