I have a few 350's and two of them have the same block numbers and one is differen't.

According to Mor-Tec they are as follows;

#3970010....350...69-80...2 or 4 bolt main
#3970014....350...70-76...2 or 4 bolt main (have 2 of these)

The 3970010 that I have has some extra webbing in the back of the block where the trans bell housing mounts up and it is a 4 bolt block. Is this a beefier better casting than the 3970014? Whats the deal with the 3970010 block? I see that it was also used for the 302 and 327.

 

010 blocks are one of the most common and sought after 4" bore blocks. If it's a 4 bolt, there's a good chance it came out of a pickup truck. As you can see, casting numbers don't mean too much. High nickle blocks will have more casting numbers behind the timing chain.

Get the VIN and suffix number off the blocks. It's stamped on the pad in front of the passenger side head. From those numbers, you can tell exactly what vehicle it was out of.

 

OK, I read another post a few minutes ago on the same topic, and decided to get off my butt and get the rest of the numbers.

My block is;

3970010
15J188280
V0102CMJ (Made Jan. 2, XXXX)
010 ( 1% nickle?)

EDIT:
I must also add that the block has 7 bell housing bolts vs. 6, I have always heard the myth that this means its a "truck block" but there again these things most always end up being false as I helped a friend of mine pull the original 350 out of his 70 Nova and it too had 7 bell housing bolts.

 

CMJ was used on a 350 and a 305. With an 010 casting, it's not going to be a 305 so it's a 350 block.

1974 police engine. It originally had a TH400 behind it. It was used in full size cars. My guess would be Caprice and Impalas plus any other full size police car in 1974.

I have no idea on the 7 bellhousing bolts. The powerglide trannies had a boss on the top of the bellhousing where that seventh bolt would be but I've never seen one drilled out. Maybe it was something specific for a police package.

 

From what I've read, all SBC's have one unused bellhousing bolt hole, or at least a spot for it. It was used on early sbc's, like in the '50s, but hasn't been used since, but was never removed either.