[Clyde]

I installed a 44121C on my 1966 GMC 3/4T PU,351 V6, I made the adapter for it. I also installed an HEI from an Buick V6. I had to lean out the carb a little. The GMC has 4.10 rear, AT400 and a gear vendor OD which drops the RPM's 500, I average a little over 12 MPG mixed driving. The engine starts much better and runs better, great up grade. I have to thank the fellows before me on this forum for the information. You will not disappointed in the Holley 500.