Anyhow, it looks like that Vito is a Model 35, which is the Vito-branded Leblanc System horn. You can tell that by the three "braces" on the G# vent key that your thumb is covering in
your first pic.
(Note: the "three brace" has been my easy way of telling Model 35 against the other models, like the Duke and Model 38. There are a couple links on Doctorsax that say "Model 35," but they aren't Model 35s. Or Vito played with their model names. Or I've been wrong for awhile
)
Looking at the serial number chartage over at Doctorsax, I'd say 1959-1961, depending on the other digits in the serial number.
The horn you've got there looks to be in really nice shape. Please share more pics!
I've got a little more data on the Leblanc System and Rationale variants
in my blog.
==========
I played a Vito tenor, which was probably a Duke, for a little while in high school many, many years ago. I still remember the funky keywork mechanisms and remember them going out of whack quite often.
I've heard others say that the Leblanc-badged Leblanc System horns had remarkably good intonation. I don't remember that one way or another about the tenor I used.
!