2000 Dodge Ram-barely moves in any gear

2000 Dodges Ram V-10 3/4ton truck [2500 engine]It barely moves when in any gear, like something is slipping. Hydraulic fluid is full. I shifted through all gears and there is no grinding. Could it be the clutch?

If this is a manual transmission, it well could be the clutch slipping. How many miles on this clutch?