This power steering box seal kit can seal up that leaky box in 1971 - 1973 Mustangs.

also suits the following cars with a Saginaw box:

American Motors
Ambassador 1966-1971, 1973-1974
AMX 1968-1970, 1978
Concord 1978
Gremlin 1970-1978
Hornet 1970-1977
Javelin 1968-1974
Matador 1971-1978
Rambler 1969
Rambler Ambassador 1964-1965
Rambler American 1968
Rambler Classic 1964-1966
Rambler Marlin 1965-1967
Rambler Rebel 1966-1967
Rebel 1968-1970
Buick
Apollo 1973-1975
Centurion 1973
Century 1973-1978
Electra 1977-1978
Estate 1964, 1970, 1973, 1977-1978
Gran Sport 1965-1972
Invicta 1963
Le Sabre 1964-1978
Regal 1973-1978
Riviera 1977-1978
Skyhawk 1975-1978
Skylark 1968, 1970, 1972, 1975-1978
Special 1967-1969
Sportwagon 1967-1972
Wildcat 1963-1966
Cadillac
Deville 1977-1978
Fleetwood 1977-1979
Chevy
Bel Air 1965-1975
Biscayne 1965-1972
Brookwood 1969-1972
Camaro 1967-1978
Caprice 1966-1978
Chevelle 1964-1973
Chevy II 1968
El Camino 1964-1978
Estate 1969-1970
Impala 1965-1978
Kingswood 1969-1972
Laguna 1973-1976
Malibu 1965-1967, 1973-1978
Monte Carlo 1970-1978
Monza 1975-1978
Nova 1969-1978
Townsman 1969-1972
Vega 1971-1977
Ford
Bronco 1975-1977
Country 1965-1969
Custom 1965-1969
Elite 1975-1976
Galaxie 1965-1969
LTD 1965-1969, 1977-1979
Mustang 1971-1973
Ranch Wagon 1965-1969, 1972-1974
Ranchero 1972-1979
Thunderbird 1977-1979
Torino 1972-1976
GMC
Caballero 1978
Sprint 1971-1977
International
1010 1971
1110 1971
1210 1971
1310 1971
1000D 1969-1970
1100D 1969-1970
1200D 1969-1970
1300D 1969-1970
Scout 1972-1980
Jeep
Cherokee 1974-1978
CJ 1972-1986
Commando 1972-1973
DJ 1975-1983
J-Series 1971-1988
Wagoneer 1971-1978
Mercury
Colony Park 1965
Commuter 1965
Cougar 1971-1979
Marauder 1965
Montclair 1965
Montego 1972-1973, 1975-1976
Monterey 1965
Park Lane 1965
Oldsmobile
442 1967-1971
Calais 1978
Custom Cruiser 1972-1978
Cutlass 1961-1963, 1966-1978
Eighty-Eight 1972-1978
F85 1961-1972
Jetstar 1964-1966
Ninety-Eight 1977-1978
Omega 1973-1978
Starfire 1975-1978
Vista Cruiser 1964-1975
Pontiac
Acadian 1968-1971
Astre 1975-1977
Beaumont 1966-1969
Bonneville 1976-1979
Catalina 1966-1978
Executive 1969-1970
Firebird 1967-1968, 1970-1978
Grand Am 1973-1975, 1978
Grand Prix 1969-1978
Grand Safari 1975-1978
Grandville 1973
GTO 1966-1973
Laurentian 1965-1974, 1976-1978
LeMans 1967-1978
Parisienne 1965-1974, 1976-1978
Phoenix 1977-1978
Safari 1967, 1969-1970
Strato-Chief 1965-1969
Sunbird 1976-1978
Tempest 1967-1970
Ventura 1971-1977
VAM
Gremlin 1977