Seeing an opportunity to improve on their fleet, engineers in Savannah decided to modify the Gulfstream G-IVSP into something a little better. For that occurrence, they decided to rename the aircraft with serial number 1500 from “Gulfstream G4” back down to its original name of “Gulfstream III.”
The SP portion of the name was removed and it implied special has been done – sure enough it had! The modifications included strengthening landing gear as well altering wing designations for airframes 1214 through 1500.