I have the same problem with my 77 crew 4x4. I drove this truck about 40,000 miles with the 400 with no problems. Then I swapped in a 460 using a L&L kit with their flywheel, clutch, and pressure plate. Put in a new throw out bearing and pilot bushing to boot. Now the clutch is very hard to depress. no such thing as a smooth shift. My wife can't even begin to drive it. Called L&L and they said to drive it a while. It's been 5,000 miles now & not any better. Please post if you find out anything.