Yes, that cover is used with the aluminum water pump.  You can see the impeller sticking out the back of the pump, and the timing cover forms the pump rear cover.  It was changed in late 65 so the pump was cast iron and was self-contained with a steel plate on the back so the timing covers did not corrode so bad.

Alot of posts went by before we finally got the information out of you as to what cover you have!

You did, in post #5.  The tipoff was the 65 model year, that could have been two different ones.  Glad we got that solved !

I am wondering if you could use the 66-69 timing cover if you changed to the iron (or aluminum aftermarket) 66-69 water pump?  Seems like brackets are same for either.  The 66 style water pump is less prone to leak.