Truck Repair: thumping into gear, hesitation problem, chevy silverado

Question
I own a 1990 chevy silverado with a 350-5.7 liter v8.  I'm having trouble with my clutch fan staying on too long and makes quite the thump when stwitching into the first gear, but when warmed up not so much. it also hesitates off intial take off.

Answer
"Thump switching to first"? If that is from Rev to 1st gear,that sounds like a bad U joint.Fan clutch works on temperature from the radiator/ac condensor.Mine stays on when I first take off for a bit.Dont know about the hesitation problem,sorry.Im a diesel tech.