Kubota L3830GST, B7500HST, BX2660. Formerly: Case 480F LL, David Brown 880UE
A quick google search for a "Case 310 distributor" comes up with: Case
If that isnt it and you are looking for used parts, try Wengers of Meyerstown or Crawler Haven
The Crawler Haven site says that that they are currently parting out a Case 310C, so you might be in luck.