1995 Jeep Cherokee Jerking at 50

The jeep just started jerking at 50 mph and I thought it might have been electrical so I replaced cap, rotor plugs, and plug wires then took it out for a test run, about 1/4 mile down the road it jerked once made a whirling grinding noise and now it will not engage into any gear forward or reverse, there are no strange noises coming from engine or transmission

checked fluid levels all okay

is it the torque converter or is it time for a new tranny