Park Avenue does not have a single zip code. It crosses several (more than 25) as it runs from Fordham University in the Bronx to the Grand Concourse in SW Manhattan. If you go to the USPS site, you can type in the exact address to get the zip code or codes for the location and addressee. Note that some addresses, especially business addresses, may have more than one zip code as well as specific Zip+4 codes for individual companies.
Eighth Avenue runs from 12th Street to 159th Street, and passes through 13 of Manhattan's zip codes.
You can refer to the list below, or, ask your question again, this time specifying an exact address or cross street.
Eighth Avenue from 12th Street through 14th Street: 10014
Eighth Avenue from 15th Street through 24th Street: 10011
Eighth Avenue from 25th Street through 35th Street: 10001
Eighth Avenue from 36th Street through 41st Street: 10018
Eighth Avenue from 42nd Street through 48th Street: 10036
Eighth Avenue from 49th Street through 58th Street: 10019
Central Park West* from 59th Street through 77th Street: 10023
Central Park West from 78th through 91st Street: 10024
Central Park West from 92nd Street through 110th Street: 10025
Frederick Douglass Boulevard from 111th Street through 120th Street: 10026
Frederick Douglass Boulevard from 121st Street through 133rd Street: 10027
Frederick Douglass Boulevard from 134th Street through 145th Street: 10030
Frederick Douglass Boulevard from 146th Street through 159th Street: 10039
NB: Central Park West is 8th Avenue from 59th through 110th Street. Frederick Douglass Boulevard is 8th Avenue from 110th Street to 159th Street
The zip code for all of East 82nd Street is 10028.
The zip code is 10019. Source: I used Google Maps to find restaurants on 50th and 8th. Then I Googled the exact addresses of the restaurants (including their zip code).
The zip code for 25 5th Avenue in Manhattan is 10003.
The zip code for 98th Street and Fifth Avenue is 10029. In fact, the zip code for all of East 98th Street is 10029.
The zip code for all of East 68th Street in Manhattan is 10065.
The zip code for all of West 77th Street is 10023, EXCEPT for West 77th Street between Central Park West and Columbus Avenue, which is in the 10024 zip code.
The zip code for all of East 99th Street is 10029.
The zip code for all of West 72nd Street in Manhattan is 10023.
The zip code for all of East 34th Street (from 5th Avenue to the East River) is 10016.
The zip code for all of East 84th Street in Manhattan is 10028.
The zip code for the Manhattan Psychiatric Center, at 600 East 125th Street, is 10027.
The zip code for East Houston Street through 14th Street, from 4th Avenue to 1st Avenue, is 10003.The zip code for East Houston Street through 14th Street, from Avenue A to the East River, is 10009.
The zip code for all of East 85th Street (from 5th Avenue ---> East River) is 10028.
The zip code for all of West 33rd Street (from 12th Avenue to 5th Avenue) is 10001.The zip code for all of East 33rd Street (from 5th Avenue to the East River) is 10016.
The zip code for all of East 93rd Street in Manhattan is 10128.
The zip code for East 5th Street, from Cooper Square through 1st Avenue, is 10003.The zip code for East 5th Street, from Avenue A through Avenue D, is 10009.
The zip code for East 2nd Street, from the Bowery to 1st Avenue, is 10003.The zip code for East 2nd Street, from Avenue A to Avenue D, is 10009.There is no West 2nd Street.