1970 LID ONLY (disc brake master cylinder)

[6bblgt]

original factory 1970 ONLY lids with "J1703" stamping

E-body $300
B-body $200

[Floyd]

@6bblgt  Dan - What's the difference between E and B-body lids?

[JH27N0B]

B body lid is narrower and maybe a bit longer.
The B Body lid actually had a different callout stamped in it for 67-69.

[Cuda_mark]

B body lid is narrower and maybe a bit longer.
The B Body lid actually had a different callout stamped in it for 67-69.

Gotta wonder why Mopar made 2 different lids. Couldn't they have just used the same one for both???

[Floyd]

The circled area appears unique to the B-body style?  Also, is looks like the B-body cap isn't vented?

[JH27N0B]

The geometry of the E body disc master cylinder is much different than the geometry of the top of the 67-70 B body one.
The E body lid was the same shape for 70 through 74 though so will fit several different master cylinders.
The B body lid is actually almost identical to the shape used on late 60s disc brake Fords.

https://secure.cougarpartscatalog.com/17257/31339/cap-master-cylinder-disc-brake-premium-repro-1969-1972-mercury-cougar-/-1969-1972-ford-mustang-/-torino.html?a=GoogleProductSearch&gclid=EAIaIQobChMI74HO17CZgQMVSCizAB1JUQXuEAQYCCABEgJbmPD_BwE&pk_campaign=689785599&pk_content=154423720703&pk_kwd=&pk_medium=cpc&pk_source=GoogleAds&sessionthemeid=26

[Floyd]

Thanks Brad - I'm guessing the E-Body style was also used on the 191 Hemi master cylinder in 70/71.  So, technically a 70-71 Hemi B-body would use the "E-body lid"?

[JH27N0B]

The 9171 and 9191 castings are identical except for the 9191 having a boss on the bottom that got tapped for a piston retainer bolt, and of course the casting numbers.
So the lids were the same.  The lid also appears to be the same one that was used on the '71-74 disc brake master cylinders with casting number 3461187, and a manual disc master with a casting number that ended in 9271.
And probably the same used on the mid to late 70s disc brake master used on B bodies and F bodies and so on until they started using a master cylinder with a plastic reservoir around '79.
The 1703 information stamping was used in 70 and probably in 71, but I never had any '71 date coded NOS MCs to look at to see what info was on the cap, the ones I've seen with date codes from 72 on had no info stamped in them. Resto Rick offers a service to stamp a plain cap with the correct info so a NOS or used plain cap can be made correct.
Of course by sometime in the late 70s the caps started having a little novel stamped in them about brake fluid and instructions on its proper servicing that would never be correct for a late 60s early 70s car, they are only good for a spare or to use on a driver.