I have a 1977 CruiseAir Motorhome with sto...

Possibly Ujoint going bad or driveline may need to be balanced-could also be a tire out of balance-another idea could be loose flex plate on engine or torque convetor bolts loose!!! :)

tank an oil sample from trany see if there is any signs of metal cuttings or the texture of sediment looks like metalic paint, thi may be a sign of a failed bushing or bearingand components may be out of alinement and touching housing giving you tha pulsing unit may need overhauling or replacing a junked in good condition whould but cant garenty service life as with a rebuilt or exchanged unit