Hy Bears63, your 71 is the first year for front disc brakes, does it have front discs, or is it still all drum brakes? The master cylinder listed for a 1970 C10 with manual brakes is Napa p/n UP36239 $78.49 thats a new cylinder, they also list p/n SS4736239 $37.49 also a new cylinder, and p/n TS101329 $29.89 + $11.10 core that is a reman. cylinder, these are all 1" bore. 1971 C10 with power brakes [no non power brake option listed] p/n UP36280 $71.49 that is a new master cylinder, also p/n SS4736280 $37.49 also a new cylinder, and p/n TS1013399 $26.79 + 11.10 core, that is a reman. cylinder, and p/n TS101511 $34.99 + $16.70 core, also a reman. cylinder, these are 1 1/8" bore, hope that helps.
