The "TML" suffix is this from the nasty Z-28 website:

1974 TML 350 van & bus 145(HP) 2(bolt) C-10 & 1500
1980 TML 350 van, bus, m/t, Cal M LT9 170(HP) 4(bolt) C-30 & 3500

 

What are the full casting numbers of the blocks? That will tell the story.

 

The casting #'s on the back of the block are 3970010

 

I have another 350 4-bolt main short block that has the casting #'s 3970010 but it does not have the 010-509-020 under the timing chain,or any of the other #'s as well.so what am I looking at. Thanks for the input Camaro BOB

 

I forgot to tell you that the dip stick is on the drivers side of the block

 

A 509 casting 400 block has the numbers "509" cast into the sides of the block in big letters -- like 1" tall.

The 350 block will not and the 509 under the TC cover doesn't mean its a 400 block or a "509" casting.

 

the suffix code you give TML is for a 1974 Chevrolet Van 350 engine. cast 3970010. It had 145hp and a 2 barrell carb. RPO: LF-5

 

The casting #'s on the 400 block are 3951509,it has the steem holes between the siamazed cylenders and it does "NOT" have 509 cast on the side of the block.I ran the #'s on this site and they told me thet it was a true 509 400 and that it came out of a 74 chevy taxi cab.The 350 has the 4 bolt mains and the 509 #'s and the 010 020 ,and if this is a 74 van 2 bl engine why would it have the 4 bolt mains and the #'s like the ones on it ,,,Is this a good block to build a 383 with or not.THANKS Camaro BOB

 

That's interesting, I thought all the 509 castings had "509" cast into the sides of them like mine. Mine is a 71 casting out of a truck.

I think your 350 block would be good to build a 383 with, but you never know for sure until you get it to the machine shop. If its standard bore and will clean up good at +.030 you are in good shape.

Personally I prefer pre-75 blocks because they were still made in USA -- I think it was 75 or 76 they started making them "Hecho en Mexico"

 

This block does not have the "hecho en mexico" anywhere on the block.