Hi all, I finally have some numbers. This is off the 71 El Camino, 78 olds Cal High Alt Q-jet, 3.08 rear.
Rear of Block Driver's side: 397004
Front Pass side: T0624CMR
I visited the Mortec site but had no luck. Am I missing a Block Casting Number? I just checked again and there is a possibility that the "4" is stamped over something else. What in the world do I have in this car? Thanks

3970014 is a 1969-79 350 block

If that is that case, CMR could be one of these engines

CMR- 1974 Chevelle 350-145hp TH400 trans, 2-bbl carb RPO L65
CMR - 1978 Corvette 350-220hp TH350 trans, 4-bbl carb RPO L82

If the casting is not as I listed, then it could be this;
CMR - 1980 Impala 305-155hp TH350 trans, 4-bbl carb RPO LG4

So you have 3 choices, will need to find the block casting date to determine what it is.
Next to the CMR there should have been another series of digits, did you find any?
If not, look at rear engine flange up from oil filter, on rough surface, i.e. 10R123456