Does anybody know the story behind this episode?

It's titled "His Two Right Arms" and it guest stars Bill Daily and Isabel Sanford.

It totally looks and feels like a pilot for a spinoff series since there's 5 characters who get more screen time that the regular MTM cast and it takes place mostly outside of the usual WJM and Mary Richards' apartment sets.
It feels like Mary is a guest star on another show.

I've looked throught my two MTM books and there's no mention of it being a pilot - but my seasoned eyes tell me otherwise.

Does anybody know the story behind this episode?

It's titled "His Two Right Arms" and it guest stars Bill Daily and Isabel Sanford.

It totally looks and feels like a pilot for a spinoff series since there's 5 characters who get more screen time that the regular MTM cast and it takes place mostly outside of the usual WJM and Mary Richards' apartment sets.
It feels like Mary is a guest star on another show.

I've looked throught my two MTM books and there's no mention of it being a pilot - but my seasoned eyes tell me otherwise.

Yes, I believe I read somewhere that it was. I'm not sure where, but if I ever remember, I'll post it here.

Kristen

From All Move Guide:

... and the season finale, "His Two Right Arms," originally designed as the pilot for a spin-off series starring Bill Daily as a stupid politician. (The pilot didn't sell, but Daily was hired on the strength of his performance as a regular on MTM Productions' The Bob Newhart Show.)