Just a thought looking in the classified's, ltman has a set of G heads for sale and it has the marking like one of the sets I have which were cast in Dearborn (the ECZ-G is in a small tag on the casting) vs the Cleveland having large casting letters with no tag. also the Dearborn ones I have the tags are upside down.
The question is does anybody know how many were cast at each facility and are there any differences in them?

55 Vicky & customline
58 Rack Dump, 55 F350 yard truck, 57 F100
59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?