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It is automatic, Jeep Wagonner Limeted from 1994. I would love to know your opinion since the problem persists.

Okay does the car itself thumps when you select reverse gear?

I doubt it's your driveshaft... it sounds like internal gearbox problems... try making sure that the oil is on the level it should be... perhaps an oil change... but either a oil check or oil change would not fix that.. I think it's wear inside the transmission... clutches

Yes, I will check the gearbox and oil levels, I think it makes a lot of sense. Thank you very much for your support and recommendation!

If it doesn't drive bad it might be a sticky solenoid or something along that line.