The mounting surface has solid sides for added rigidity and to help keep the manifold flat for proper blower seal. It also has been machined for a thermostat to allow use on the street and the floor has been radiused to allow better fuel distribution. The manifold is 3.90" inches high overall and the HEI distributor can't be used with the 8-71 blower. Ports measure 1.875" x 1.125", drilled 1/8" NPT in the rear for a boost gauge and includes a backfire valve assm. for those little mishaps.
Manifold can be purchased satin or polished aluminum finish from drop down menu.