The problem is that the fittings on the fp are fixed 5/16 inlets/outlets. Here is the fp
CARTER - 383, 440, 5.5 tp 6.6 psi
1969-71 Muscle Car Series, Chrysler, Dodge, Plymouth
$34.95
CARM4589
I am not sure that it is an HV Carter fuel pump. Does anyone have a part number for an HV? Maybe I can return it and get one that has the npt's on it and get the 3/8 fittings.