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Help ID Master Cylinder


Well-known member
Mar 11, 2002
End of the Ike, IL
1968 Lemans Blue Roadster
I'm trying to determine if a master cylinder I have is correct for my '68 w/ PB. It was in a box with some other parts I got when I bought her some years back. I know that the MC presently bolted on is not original.

The casting number is 5460346 (or, if my old eyes didn't quite get it right, 5480346.) There is a stamped "D2" on the bleeder side. It has two bleeders above the holes where the lines would connect.

Thanks in advance.
The D2 is likely a mold number....the mold in which the part was cast. Look for the Julian date, as C5D said. Chuck
Re: ID

c5d said:
BlueL36, 5460346 is an original part number, power brake, for at least '67-'73. If you find a 4 digit number, that is the julian calendar date stamp. The first three numbers = day of the year, the last number = year (i.e., 3659 = 365th day of 1969).

C'ya & Happy New Year,

This is not always the case. I have a Sept 11, '73 built 1974 Corvette and it's m/c is dated "3004". Can't be the three hundredth day of '74 since the car was built in '73 :confused

In judging mainly '73-'82 Corvettes I have seen this many times where the year is the first digit, next three numbers are the day.
Same part #

I have what appears to be the same master cylinder number on my 74 Coupe which is also a 9/73 production car. Man, it's hard to read upside down !

Regarding the "upside down" and/or "rightside up" casting number, they come both ways. Don't remember which is which, but one designates that the MC was cast on the "night shift", while the other designates it was cast on the "day shift". Chuck

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