I bought one of those $20 reproduction master cylinder covers to replace my ugly original in a 73 Z28. When swaping them I did a comparison and the repro does not have the same stampings in it. The most interesting stamping on the original is a number that looks like a date code (J1703).
Could this be a date code and if so what does it decode to? If the J is for the month like in other codes it would mean October but the car was built in June. All other numbers on the car are correct so maybe this isn't a date code.

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Mike Dixon

How about if J=Julian and 170th day which is sometime during June and 3=73 ......?????
Chuck Sharin

Chuck, thanks. Is that format of date coding used on other GM components? Where could I go to see it used?

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Mike Dixon

I have a rebuild on my 70, has the same stamping on it. Maybe coincidence or a part number? Also says Delco brake fluid and Delco Moraine.

I just checked the original cover for my 70SS. It has the following stampings.

1.Service with Delco parts

2.Use SAE J1703 Delco Brake Fluid.

I suspect that #2 refers to the old J1703 brake fluid specifications. It is still referenced here.

http://www.conti-online.com/generator/www/com/en/ate/ate/themes/products/brake_fluid_en.html

Bingo--- it is the brake fluid spec.
Thanks to all for the help, now where can I get the original replated with
zinc-dichromate?

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Mike Dixon

I got mine coated at brakeboosters.com, and did my booster and proportioning valve bracket done at the same time. I think the guys name is Steve Gregori and I would recommend him. Pretty quick turnaround and nice to deal with. Here's his web address: http://www.brakeboosters.com

Good luck!

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Daytona Yellow, 1970 RS/SS 350

I used Steve Gregori also. He did a great job on mine.

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Buddy
1970 Z/28 and
2002 35th Anniversary SS

Gary S, YOU are THE MAN......shows how much I DONT KNOW !!!!!!!!!!
Chuck Sharin

<font face="Arial,Verdana" size="2">Originally posted by CamarosRus:
Gary S, YOU are THE MAN.....</font>


I just got lucky on this one. If my cover didn't plainly say "Use SAE J1703 Delco Brake fluid", I wouldn't have known either. Once I had that little piece of information, a Google search confirmed it for me.

I'm also guessing that you won't find repro covers with this fluid specification because J1703 was superceded by newer specifications, so this printing will be year specific for the years when it actually existed, and this same cover fits a lot of newer models.

<font face="Arial,Verdana" size="2">Originally posted by Gary S:

I'm also guessing that you won't find repro covers with this fluid specification.....</font>

The reproduction cover I have (but now is going to be an ashtray) says "use DOT 3" brake fluid. It also does not have "general Motors" or "Delco=Morraine" stamped into it. The plating is nice though!


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Mike Dixon