You can get a 30" slide in range.

36" ranges are free-standing.

AFAIK nobody makes the 70's style drop in ranges.

What is your price range?

Blue Star or possibly some other old copycat sites sometimes mistakenly(?) use the term "drop in" when the more common "slide in" is the commonly accepted term for the same configuration description today.
(Fake) "drop in" sometimes also occasionally show up as a semi custom aftermarket piece of cabinet attached to a range bottom drawer.

drop in range

slide in range

Apparently, all the current drop in ranges are electric and 30" or smaller.