Things are a little complicated for a few years around that time. This info is from the Ford Truck Parts Book, I'm not an expert on these trucks. Maybe someone else has additional info. A little more info on what you are working on would help my answer, exactly which vehicle and which engine? Here's some general info:
F100. F250 and F350 are all light duty trucks and had a 352 if they were FE powered in 1965 & 1966.
1965 F100 & F250 4x4 and F350's used Timing cover part number C4TZ-6019-D.
1966 F250 4x4 and F350 also used this cover. The 1966 F100 4x4 did not.
This also the same cover used on 330 c.i. FT Medium duty truck engines from 1964 on. There was also a 330 c.i. FT heavy duty truck engine which is different and uses a different C4TZ-6019-E timing cover the same as the 361 & 391 FT engines. The heavy duty FT's use the different water pump.
1965 and 1966 F100 & F250 4x2 and the 1966 F100 4x4 used the same cast aluminum timing cover as the passenger cars as did all the 1967 to 1971 light duty trucks.
Keep in mind these are PART numbers not the CASTING numbers you will see on the part. Ford sold replacement timing covers as a kit including a gasket, a couple timing pointers, screws, etc. so you will not see C4TZ-6019-D on the cover, but it should help to figure what will interchange.
