Allied Signal Avionics GNS-XL-FMS Flight Management System. P/N 18355-0101-0004. Software mod. 2 and Hardware Mods. 1 & 2. S/N 1124. This FMS was removed in working condition from another Gulfstream we have parted out. We always offer a full refund if not satisfied with your purchase. Buyer pays $20.00 shipping FedEx ground in the USA. Ship USA only. US bidders only.