I know that Eb from GREEN ACRES was in a couple of the crossover episodes of THE BEVERLY HILLBILLIES and he also appeared on PETTICOAT JUNCTION a couple times, but were Mr. and Mrs. Ziffle, Mr. Haney, Mr. Kimble and Alf and/or Ralph Monroe ever in them?

Mr Ziffel appeared in several B&W episodes of Petticoat Junction and 1 episode of the Beverly Hillbillies (Drysdale and Friend). Mr. Haney appeared in 3 episodes of Petticoat Junction but never appeared on The Beverly Hillbillies. Mr. Kimble and the Monroe Brothers never appeared on either show.

Mr Ziffel appeared in several B&W episodes of Petticoat Junction and 1 episode of the Beverly Hillbillies (Drysdale and Friend). Mr. Haney appeared in 3 episodes of Petticoat Junction but never appeared on The Beverly Hillbillies. Mr. Kimble and the Monroe Brothers never appeared on either show.thank you.
What about Arnold and Doris Ziffle?

I'm pretty sure that Sam Drucker appeared in all three.

Did "Uncle Joe" Carson ever appear in Green Acres? Seems like he would have made a good antagonist for Oliver.

Did "Uncle Joe" Carson ever appear in Green Acres? Seems like he would have made a good antagonist for Oliver.

yes. a few times

thank you.
What about Arnold and Doris Ziffle?

They both appeared on Petticoat Junction, but neither appeared on The Beverly Hillbillies.