Help finding the year of my engine

[straight6chevyguy]

I been trying to find out the the year of the engine in my 1965 c20 (it seems simple I know) but have ran into some confusion.
Engine is: 292 Inline 6
First off I am 100% positive that it is not the original engine to my truck.

So here is the numbers I have gotten off the engine:
Stamped pad behind the dist.: F0902UH

Numbers on engine block: CON2 H264 3851659 (the 9 could be an 8 Its hard to read)

So the LMC truck catalog says UH could mean 1965 or 1966 Is there anyway of knowing witch it is?

All so in the past I read about the casting number being the date code but when I decoded that I came up with 1964.
Maybe I'm just looking at some thing wrong?