Brake Master Cylinder - Proportioning Valve Numbers

[08sky_way]

I am replacing the original PBR master cylinder with a new after market unit. The Gregory's states that the 'new master cylinder must have the same proportioning valve number stamped on the front of the cylinder'. There are two sets of numbers on each of these units - the old PBR has 13E4 and C-24. The new one has 84M and 8J. The seller did not ask for the the numbers on the original unit to be supplied. I don't know what these numbers mean. The external physical characteristics of the new cylinder is the same as the old with just a few minor changes in the casting. Should I proceed with the installation of the new unit?

[markovr]

The proporting valve number is the "crack point" of the unit and for most pre vs cars is 2.4 and its the pressure the valve works at...restricting pressure to the rear brakes to limit a rear end lock up under emergency stop.

[BlackVXGTS]

VR Commodore master cylinder crack point is 2.4, VS is 3.1 (MPa).

[08sky_way]

Thanks for the replies guys. I gather then that the C-24 on the old unit means 2.4 MPa crack point. The new master cylinder has only the numbers 84M and 8J which don't mean anything to me. I think I'd better research this a bit further.