I started working for Chrysler in Highland Park, MI in 1969, and all I can say is that I have personally thought that Chryslers in general did sag in the back a little compared to the front when brand new, and I never liked them that way - they always needed a little rake (slight though) to look correct in my eyes. So although this photo of the 67 doesn't necessarily prove anything, I do generally agree with Stan. I have always wondered why and have questioned whether being slightly lower in the back would slightly minimize rear "wheel hop" even when new during panic stops. It was a problem that was well known in engineering back then.
This video shows a new 1971 Chrysler New Yorker 2 door test car undergoing magazine testing, and the low rear end look is also present throughout, and the panic stop wheel hop is highlighted as perhaps the cars greatest weakness.