It has somehow morphed into obscure trivia about some of the actors.
A little help here?
What is the connection between Leonard Nimoy and Lee Marvin?
I also have a clue, it involves a western.

While not in a western, Nimoy appeared in two episodes of Marvin's M Squad.

http://imdb.com/WorkedWith?name=Nimoy%2C+Leonard&as=a&with=a

I see that, not necessarily an appearance then, although I don't know what else it could be.

The word "connection" was what was used and clue #1 was it had something to do with a western.

But thanks DG.

Any new ideas anyone???

They appeared in the following series, though not in the same episodes:

Dragnet (Hey, LA is West.)
Wagon Train
Bonanza
The Virginian


Both were in a Western whose title began "Cat".

Catlow


Cat Ballou

(Actually, Marvin was in another Cat Western, "The Great Scout & Cathouse Thursday".


I tried a Louis L'Amour connection, but I couldn't see a link to Marvin.

Thanks DG, it's got to be in there somewhere!