Boggie, thanks for pointing out the hump. I just ordered one from NAPA based on 1965 Dodge WM300 1 ton wagon. That truck only used the 251 flat head 6, aka L6. I'll go over the pictures to see if I goofed! They had 2 in Alaska, 0 lower 48, manufacturer has 7. BTW NAPA has the WM300 on web site but not on the store computer.
After looking at pictures it looks like NAPA one has the hump, I think. Would make sense as according to vintage power wagons the one with hump works with both Canadian and US engines.