The brake master pump is replacement for OEM 4746398, M39649, 18013978, 18060087. And the summary of the application is 1988-1994 Chevrolet, 1994 Dodge, and 1988-1994 GMC. It has 1.25 inches bore diameter piston. As for the application details, please check the following information:
Chevrolet
Blazer 1992-1994
C1500 1988-1993
C1500 Suburban 1992-1993
C2500 1989-1994
C2500 Suburban 1992-1994
C3500 1988-1993
C3500HD 1992-1994
K1500 1988-1993
K1500 Suburban 1992-1993
K2500 1988-1994
K2500 Suburban 1992-1994
K3500 1988-1994
Dodge
Ram 2500 1994
GMC
C1500 1988-1993
C1500 Suburban 1992-1993
C2500 1988-1994
C2500 Suburban 1992-1994
C3500 1988-1993
C3500HD 1991-1994
K1500 1988-1993
K1500 Suburban 1992-1993
K2500 1988-1994
K2500 Suburban 1992-1994
K3500 1988-1994
Yukon 1992-1994