Block Castings

[6.2puller]

I have an engine here that was removed from a 79 K5 Blazer and the VIN denotes a 305 V8 2bl carb.
The casting number on the back drivers side of the block is 3970010
Wich by my research means
3970010....302.....69....4...Z-28 Camaro
3970010....327.....69....2...Trucks and industrial
3970010....350...69-80...2 or 4

So if the motor were a 79 it would be a 350 but we know by the VIN it is not original.
Any ideas on how to determin this other than pull the oil pan? It is still a complete engine with TH350 so I can't stick it on the stand yet to pull the pan.

 

[MTChevy]

ive noticed on 350's on the back where you got the number, the blocks that ive seen say GM 5.7L

 

[thedrip]

The number of "0010" 350's vastly outweighs the number of 327s, and it's guaranteed you don't have a 302 on your hands. Theres also the matter of 2 bolt vs 4 bolt, you can't tell that one externally, drop the pan, or get a scope, drain the oil, and perform surgery through the oil plug.

 

[sweetk30]

the 5.7 or 5.0 is only on the efi blocks as i have seen. if you have the tranny off and fly wheel or flex plate off you can look at the crank flange and match it up to a pic in some of the books and that will tell you what you have as far as 305/350 so on.