Connecticut first added A117.1-1961 to the State Building Code (as Article 22) in 1972 so, depending on when the permit was issued, there may not have been any accessibility requirements. The edition of A117.1 adopted in 1972 was the 1961 edition. It was pretty basic back then. I'm pretty certain the Connecticut statute requiring a percentage of units in multi-family projects to be accessible wasn't enacted until a number of years after 1973. This means that, under Connecticut law and code, dwelling units on upper floors may or may not (but probably not) have been required to be accessible.
On the other hand, the federal Fair Housing Act was enacted in 1968 and amended in 1988, so in 1973 the original Fair Housing Act would have applied, but the 1988 amendments would not. Unfortunately, I have not been able to find a copy of the original, unamended Fair Housing Act, so I don't know what it might have required in terms of accessibility for upper story units.
Are any of the units on the second through the fifth floors designated as "accessible" units?