Corvette Proportioning Valve

[TnBlkC230WZ]

My question is does the OEM Corvette proportioning valve have the switch that cuts off the rear brakes if it thinks there is a leak in the rear? Do all 1970 Corvettes have 4 wheel disks?

I've put CPP's 4 wheel disks on my 71 Nova. These are stock style 11 inch disks front and rear. I've had numerous problems with the kit and I want/need to replace the proportioning valve. I've already replaced the master cylinder with a 1970 Corvette power disk master cylinder.

This feature in the CPP valve keeps tripping each time I try to bleed the rear brakes. I have to disconnect the rear line to reset it and start over. Do you see the my delimma?

[TnBlkC230WZ]

The CPP proportioning valve looks just like the 74 -78 Vette proportioning valve. Does the 74 - 78 Vette valve have the feature that suchs off the rear brakes if it thinks there is a leak?