Thanks Cory,
So did the 66 gt350's get either one or just the skinny ones. Could these be found on 65/66 ford automatic trucks?
Hi 65Fastbackk,
It was only the 65-66 Ford F100 and F250 trucks with the straight 6 300CID engine with Cruise-O-Matic C4 that got the "C" servo. The same trucks with the 240 CID did not. The Ford MPC shows only one set of service part numbers for both years, piston C5AZ-7D002-C and cover C5AZ-7D027-B, not to be confused with the casting numbers on the parts. They are not the same. Below is the images out of the Ford MPC for truck.
Remember in the both types of part number casting and service part:
Third character "A" = Galaxie and "T" = Truck
Forth character "Z"= Service part and "P" = Auto Transmission
The original casting shows "TP" for Truck Auto Transmission
The service part number "AZ" for Galaxie Service part.
https://classicmustang.com/decoding-part-numbers/If the Ford service parts were ordered, you could get either the C5 or C6 casting part numbers. They were considered functional identical.
Mr. TLea captureed your answer very well in reply No. 6 for your question "So did the 66 gt350's get either one or just the skinny ones?"
Enjoy
Cory