This is a non-standard 7" Dual Diaphram Brake booster for various custom applications.

   NOTE THAT NO BRACKETS are provided on the rear - only the 4 bolt flat panel studs... but if needed.. a set of Zinc Chromate finished angled brackets (shown) for 64-72 era fitting are available separately  that bolt up to the 4 bolt mount points.

Note: that the piston reach is for the mostly 69 master cylinder with the normal and up shallow piston pin depth.>

As an additional guide.. this might help people over time.... DONT JUST BLAME A PART

Don't have time to read this below ??.. but have a suspected booster issue.. then at LEAST read this link to the USA suppliers MBMbrakes who supply this stuff all day every day...https://mbmbrakes.com/brake-booster-diagnostics/

    Often referenced as needed on 64-72 A body (GTO/ Chevelle/LeMans/Skylark etc) and 67-69 Firebird and Camaro .. where a big block has been fitted.

   Sometimes used also on RHD Firebirds where hedders are used to help reduce crowding around the firewall.

    Delivery is  covered within Australia - but not to Darwin / NT or NW regional remote stations and towns.