The "Mexican Sundial Suit" (or simply "Sundial Suit", as most fans call it) was first debuted by Elvis on stage in 1974, although he only wore it for a few concerts during that year.
However, the "Sundial Suit" is probably most famous for being the jumpsuit that Elvis wore the most during his final concert tours in 1977, including his final television special on CBS in 1977 -- "Elvis In Concert". There are many theories out there amongst Elvis fans as to why Elvis chose to wear the "Sundial Suit" almost exclusively during the final tours of 1977...the one that I have heard most often is that the "Sundial Suit" was one of the only jumpsuits that Elvis was still able to fit into, considering the constant fluctuation of his weight during the final months of his life. Whether that is completely true or not, I don't know...
Hope this helps you out some Dave!!
F.Y.I!! There are many FANTASTIC photos of Elvis wearing the "Sundial Suit" which are posted in the 1970's section of the PHOTO GALLERY here at TCB-World!! We hope you will take the time to check those out!!