Shirley Jones -- XXX Proposition Went Down ... No Matter What Joan Collins Says

Shirley Jones is sticking to her orgy guns -- insisting Joan Collins' ex did proposition a foursome way back in the 60s ... even though the story's being yanked from Shirley's book.

As TMZ first reported ... Joan convinced the publisher of Shirley's autobiography, that Shirley's tale of an almost sex party with Joan and their husbands ... was untrue -- and got it yanked from all future printings of the book.

But last night ... Shirley and her current husband Marty Ingels (not the guy in the orgy) were defiant ... telling us they don't care what deal Joan reached with Simon and Schuster -- Shirley stands by the story.

So, who's the foursome fibber?