The C6AE-R head is the splitting point between original head design and the later emission heads. Ford Cylinder heads casting and Mustang Cylinder heads casting. The other alpha numeric combination, cast just in front of that block number is the block's production date. The Ford 240 (also known industrially as the CSG639i engine) has a kidney bean shaped combustion chamber. 1969 engines used head casting number 3927186 and featured the large 2. At the very least it may help you decide if it is a 289 0r 302.
The important digits are the first four and last one, two, or even three digits, in some cases. 4-barrel heads may be identified by the casting mark at the upper corners of the valve cover mating surface. When Ford designed the 351c heads back in ’68-’69, they took a look at everything else out there and squished all the best ideas from everything into one neat package. Further refinement came on the XD when both engines were offered with alloy cylinder heads made for Ford by Honda, and in February, 1983, the first fuel injected sixes were released for the XE. The older 221 and 260 Ford small-blocks are easily identified.I'm trying to find info about it but running around in circles. Ford distributor differences: The 351W and the “335”, “385” series distributors are basically identical except the gear. The one head has numbers cl 1991 and s/n sb 990-2 1181.
Ford 302 heads casting numbers 5 ,6 or 7 = year or 5th, 6th/7th year of the decade.
