Big Block Casting # Location?

[kyle's 73 sport]

I looked all over and am having trouble finding it. The engine is a 413 that came out of a 1968 30' motor-home. I found a production number that was
10/16/70.

-I thought they stopped making the 413's in 1963?

 

[tedsweet]

413s where used in motorhomes etc until the mid 70s

 

[kyle's 73 sport]

location anyone?????

 

[68383GTS]

It should be on the side of the block in big numbers not hard to miss