Help with engine casting numbers

[70burb]

Afternoon everyone,

 

Reason I'm writing is I'm in the process of rebuilding a 1970 3 door GMC suburban and I'm trying to find out some specifics on my engine casting numbers and I've come to a dead end. All the block numbers are actually letters TIOIIHN. I have no idea what this is. The guy that rebuilt the engine who builds sprint car motors for a living also doesnt seem to know. He thinks it might have been a special short run production towing package block that GM did. Any ideas out there????

 

Thanks

[Cool Zr2]

special short run production towing package block that GM did.  Any ideas out there????

 

Thanks

 

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That would seem odd, gearing is usually used to get the desired towing performance.

 

And what is a 3 door suburban? Do you mean a Blazer?

 

The casting numbers are on the back of the block on the bellhousing mating surface.

[R Dogg 56]

He's right, GM made a 3-door Suburban for Chevy and GMC in 1970

[Cool Zr2]

He's right, GM made a 3-door Suburban for Chevy and GMC in 1970

 

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That is the coolest thing i have ever seen.....

[Delray]

Those numbers came from the right front of the block,and are stamped right? the casting numbers are in the rear of the block and will be just numbers.something like 3990010 and there is also a casting date,something like E 11 0 (may 11 1970) more info on this www.mortec.com

70 Sub my brother-inlaw had one two doors on the right side and one on the left, his was whiped,smoked like a freght train and the body was ate up.

Steve

[autopat]

Actually the letters on the front of the block denote the vehicle and transmission attached to that engine (usually followed by the last 5 digits of the VIN, and they're usually hard to see through all the paint). I don't have my book with me but if I get a chance when I get home I'll decode it for you, unless someone else beats me to it. Most likely if it's a 1970 block the casting number on the back will be 3970010 (350 both 2 and 4 bolt main, high nickel) or a 3970014 (2 bolt main). There are a butt-load of casting numbers for Chevy small blocks, but the majority of truck blocks from late '69 to late '72 were the 3970010 blocks. The block in my Nova was originally a "replacement" '70 truck block, so it had no codes stamped in it for the vehicle or trans. but it was a 4 bolt main.