I have a 1971 Cutlass "S" It has a 400 in it and I am trying to locate the engine number on it. Does anyone know where I might look for it?

 

If your talking about the casting numbers. Then you need to look at the shelf its the flat area behind the water pump in front of the intake. To the right of the oil filler tube.

Also welcome to the site.

 

Right behind the waterpump in front of the intake, this area may be filled with gunk and crud, wipe it out and post the numbers here. If it is a 400 from '68-69 there will be a vin derivative on a small pad below the number 1 cylinder.