Delaney and Bonnie - Only You Know and I Know - 45 rpm

I'm not sure of the provenance of this song, I need to ask Mr. Google or something.  What's the original?  Who wrote it?  What's the cover?  Or covers? 

This is a good version, but it's not the usual Delaney and Bonnie version that you hear.  That must be later, after Eric C. joined their party, and it does always sound like a party, doesn't it? 

No, I'm  not one of those old burned out Hippies that dwells in the past, but it was a pretty happening past, when you think about it.