[BJCHEV396]

I have a '70 L78 Nova,4 speed with a 3:55 12 bolt.Last few times I've had the car out it's reving higher.At 60 MPH it used to rev around 3200.Now it revs around 4 grand at 42 MPH in 4th.I'm thinking clutch slip.But there is no clutch smell.It engages well on first gear take off.Let the clutch out in 4th gear and the car jumped ahead.Figured if there was clutch slip that it would just stay still and rev.Any help would be appreciated.Thanks.Bill.