T1I08TLM - Can you decode this!?

[Hardesty454]

That's what I thought, but it looked like an I. Another reason I ask you guys, more knowledge than I could obtain!
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[chevyman91]

at is the date code on the front passenger side pad
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[chevyman91]

That is the date code
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[Hardesty454]

Oh........ I knew that. Hahaha
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[chevyman91]

No worries. Glad I could help you after I got the suffix code right
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[SS Tim]

There are six points of information (most of the time) on 67-72 truck V-8 blocks both big and small.

Engine code on the machined block deck pad, in this case stamped T1I08TLM which is a misstamp. Being that the stamps were individual letters and numerals placed in a gang holder for striking, this is not uncommon substitution. The engine code gives use three points of information, the engine assembly plant, the engine build date and the specific application it was built for. In this case Tonawanda, November 08th, 71-72 Truck L47 402/210 C10-20 w/AR (air injection) with a TH400

Casting number is cast into the block, in this case 3999290 and it identifies the casting but not always the application it was finish machined for or assembled as. This number could have been a 68-69 truck 396 or a 70-72 car or truck 402 in addition to 2 or 4 bolt variations.

Casting date gives the rough date in a month by letter, numeric date and last digit of year. Examples for this motor might be J010 or K281.

Casting clock (circle of dots and an arrow) breaks down the date by hour and shift the block casting date. This is mostly only useful for production reasons.

[chevyman91]

I have heard that its not uncommon for them to exchange an I or L for a 1 but don't know how much truth there is to this
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[bruceman1968]

Originally Posted by Hardesty454

Could swear that's an I.

That is a I, it's a miss stamp, should be a 1. On the bright side, no need to get your eyes checked. If you have the protect-o-plate, that code will be on it. T1108TLM. Did you get the date code? It is a cast into the block.

[Hardesty454]

No I didn't grab the date code. I can!

So all in all, the block is essentially what came with this truck... I kept imaging this was something done throughout the years.
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[bruceman1968]

Yes, get the date code if you can. That way we'll know for sure that it's a 71. This is all good news for you, Original motor is a plus, and the 71 had 310hp the 72 had 210hp.

[Hardesty454]

J29 71

Jan 29 of 1971?!?

[bruceman1968]

J is October, The block was cast on oct. 29 1971. It was assembled on nov. 8th, 1971.

[SS Tim]

If your truck is a RPO L47 truck (400 CID) and the door sticker (the blue cert. label) has 11/71 in the top right corner it may very well be the original block.

[Hardesty454]

I do not have a door sticker

[SS Tim]

If you want PM me the VIN and I will try to match it with known build date trucks. This is a longshot as I need VIN and build dates close from the same plant to be anymore than a guess. It would still be a guess but not a WAG.

[Hardesty454]

I ran my VIN and it came up with the Fremont plant. However this motor is from NY. Is that common for them to be made separately?

[SS Tim]

Yes the engines were shipped to Fremont for final dressing then line installation. Your truck may be a December 71 build. Is there a build sheet in the seat back? Do you have the protect-o-plate?