The 170 Series passenger cars were cataloged only in two sets in 1924 as a 171 buffet and a 173 Observation. It would appear that IVES sold these same cars right through until 1927, but never cataloged them. After the first year the cars were numbered No. 170 buffet, 171 Parlor and 172 Observation. The 171-173 trucks in 1924 used O-gauge wheels. 

Circa 1924 - Confusing but in 1924 IVES numbered these cars 171-173 with the No. 173 being an observation.  Below is the No. 171 Buffet car to go with the above observation, Note that normally a No. 171 was a Parlor Car. To the best of our knowledge IVES never made a 172 Parlor car

This car was originally lettered 184 - Ives just painted over the number and numbered it 171.

Similar 1924 cars but these are lighted ('-3').

Circa 1924 - This is the Wanamaker version of the 1924 cars.

Circa 1925 - Above and below are the three tan cars from 1925, note the brass journals and that the baggage door moves on the Buffet where it didn't on the 1924 cars.

Circa 1926 - This car used the body from a No. 185 which had brass plates. IVES merely painted over the indentation and rubber stamped the number in it.

Circa 1925 - 1927 - The two cars pictured below have been found in a couple different sets that would appear to be from this time period. These cars were not cataloged in these sets (184 series cars were shown in the catalogs). These may have been sets that were cheapened to sell out to large department stores or something else - we just don't know.

Another example using the body a No. 186 pullman and the number is rubber stamped into the indentation for the plates.