Thanks to everyone for all of your input. It is helpful!

<TABLE class=tborder style="BORDER-TOP-WIDTH: 0px" cellSpacing=1 cellPadding=6 width="100%" align=center border=0><TBODY><TR title="Post 12013309" vAlign=top><TD class=alt2 align=middle width=125>52 Merc</TD><TD class=alt1>I agree it's an FE series engine and from the valve covers I'd guess late 60's. Most likely a 390 but there's no way to tell for sure certain. The Carter/Edelbrock carburetor is not stock, either. How long has your Dad had it? </TD></TR></TBODY></TABLE>
Dad has had the truck for at least 15 years that I can think of. He is only the second owner and was apprently given some false info on it as he was under the impression that it was basically all original.
When I was there visiting, we tried to look for some numbers so that I could research it some for him before listing it for sale but we were not able to find any numbers on it whatsoever.

All of your added input is extremly helpful when trying to sell it. I appreciate your help.

Thanks
Kris