Thanks Scott, but for some reason all the parts books i've come across list a separate part number for 450, & 470 series GMC's with full air brakes, versus one with hydraulic, or air, over hydraulic. I still had the box, from the fuel pump on your 450 series out in my shop, & was preparing to purchase the same for this 470, but noticed they (the older 531 pump, that was on your truck)& the exsisting pump on my 470 COE were alot different. The GMC Parts maunal list a prt. no. 1537007, while an older AC catalog I have list it as a AC number 7007. None of the parts houses around me can interchange that AC 7007 part number to a modern number.
