The 351 came in both heavy & Light truck versions, the light truck engine came out in 1966, it's the 351E. the heavy truck engines are the 351 with no letter, 351C & 351M. the diffeance is in the number of pison rings, light truck engines have 3 while heavy truck engines have four.
do you have any of the pistons out yet?
I know the management here dose not like it when I tell folks they should be asking these questions in the 6066 GMC Trucks Group on Yahoo! Groups, but that is the best place to find help with this or any of the other GMC Big Block V6/V12/V8 engines, we have a lot of guys that are more expert on these engines over there than what I am... And you are a member there now.
