So this came up in mepstein's classified ad http://www.914world.com/bbs2/index.php?showtopic=304055. What is the difference between the early and late brake pressure regulators? I PM'd Eric but I know he's busy and hasn't had a chance to respond as yet.
Anyone have an answer and better yet a photo of the differences? TIA

Posted these pictures in his WTB ad.

The difference is here. I believe the late style is on the left.

Early has 2 ports and requires the brass tee and banjo fitting.

Late has 3 ports and no brass tee.

Both function the same.

Late is pictured on the right in Garold's last post.

I asked Eric about this a while back- my car ('73) was missing the regulator and I asked him if it mattered if I sourced an early or late to have rebuilt and installed.

Eric's answer:

"It really "does" matter. The left and right lines would have to change and the mounting studs would be in a different place as the later regulators were mounted closer to center.

Does it have a brass "T" fitting at the top of the pressure regulator? That's the one you need for your car.

Early models have one fluid inlet at the bottom and one at the top. The Brass T then distributes fluid from the top outlet to your left and right calipers.

Brass T's must have been expensive because, in late 1974 they drilled an additional hole in the rear of the regulator (at the top). The left calipers got fluid from the original top hole and the right caliper now got fluid from the new hole in the rear... effectively creating their own T at the valve body.

The rear hole can be plugged and the factory T installed on top of a late model regulator if need be so, all is not lost.

Hope that helps.

E."

Awesome you guys... thanks for that. Cheers.

Here's the skinny, and, think "economies of scale"

Early pressure regulators had a fluid inlet at the bottom and a fluid outlet at the top. A single inlet was fine but, the outlet now needed to go to the left and the right sides of the car. A brass "T" fitting with a banjo bolt was employed to do the job.

The valve had always been bossed for multiple outlets but, only the one at the top had been tapped to 10x1. In Garold's picture above you can see the boss on the early regulator on the left (circled in green).

Later pressure regulators were simply tapped on the top "and" now the back side facing the firewall. The right side line went into the back and the left side went directly into the top. This did away with the more expensive components (brass T fitting, banjo bolt and copper washers). You can see the later one with the same boss tapped to 10x1 on the right (circled in red). Eliminating the T was a cost saving measure.

Click to view attachment

So... the down and dirty; early ones have the brass T, later ones do not. If your pressure regulator is missing you can tell by the VIN or, by your lines. Early ones have straight line ends that go directly into the T. Later ones have 90 degree bends at the end of the lines.

Just to be perfectly clear...the early regulator is the same for the six and four even though the input pressure differs. Is the correct?

Click to view attachment