1987 Chevy Blazer My distribuer wont move

My buddy bought this s-10 blazer with the 2.8 liter engine thinking the timing was off. We tried to set the timing but we discovered the distributer will not move. The engine turns over and the distributer spins and fires just fine but we cant get the distributer to pull out or spin its stuck fast. Any information on why the distributer wont move will be helpful thanks