00 STERLING With a CAT C7 WITH A 7 SPEED SPICER-ONLY REVERSE AND FIRST GEAR!!!

Any help would be greatly appreciated. Just bought a 2000 Sterling C7 with 7 speed spicer. Bought as is from a delivery company. They have no info on it. Runs fine but only has reverse and first gear. When put into 2 3 4 5 6 7 gears and let clutch out it does not move at all. Its like the gears are gone. Could there be a shifter fork or top cover issue? I have no experience with this trans. Seems odd to have first and reverse only and loose other 6 gears. If anyone could advise me i would greatly appreciate it. Thank you kindly. Gil

00 STERLING With a CAT C7 WITH A 7 SPEED SPICER-ONLY REVERSE AND FIRST GEAR!!!