ernsetp - whats the part numbers for your rail and rollers? The guy I used to work for had a bunch of Fiat's and he's got some new and barely used undercarriage components stacked up at the shop and he's selling off all his fiat's and stuff that goes with them.
Here is what I came up with from the FD9 parts book:
Drive Sprocket 27 teeth: 76004991 2ea (mine come to a very sharp point)
21.7" shoes: 76007504 - 78 ea. (the 17.7 or 19.7" shoes would be ok too)
Chain Assy: 79040785 - 2ea or
Track link right: 79056028 - 78ea
Track link left: 79056029 - 78ea
Master Link right: 79056034 - 2ea
Master Link left: 79056035 - 2ea
Pin: 79031596 - 80ea
Track Roller single flange Assembly: 76004903 - 8ea
Track Roller double flange Assembly: 76004902 - 4ea
Roller only single flange: 76004900
Roller only double flange: 76004898
Track Carrier Roller Assembly: 4991715 - 4ea
Bolts for shoes: 79031606 - 312 ea
Nuts for shoes: 70666583 - 312 ea
Bolts for master shoe: 79034204 - 8ea
there are 40 shoes per track.
The idler sprocket was changed to one from a loader I believe.