I have a block with a date code stamped in the right place, and am a little confused about GM using the letter I in place of a 1. I've been told by a Corvette expert that this is common, and they used the I and 1 interchangeably.

The code reads:

TI003CTX and it is from a 70 Chevelle with a cast date of I289 <-- If I recall correctly, which would put the build date at Oct 3, 69. Has anyone seen an I in place of a 1 on a 402 block?

I would say the "I289 should be just that, an "I". That would represent a casting date of September 28, 1969 for an assembly date of October 3, 1969. Looks OK to me. Just my two cents worth.

EDIT - now that I read it again, it is the "I" in the assembly date you are obviously asking about, rather than the casting date. Personally, I would think it would be easy for a line worker to mistake the two. Again, just a personal opinion.

Assembly date stamped on the pad, in the number that should be a 1 it is a capital I TI003CTX Has anyone else ever seen one of these?

I have a 65 Impala with engine pad number as follows: F042IHD it's a 327/300 powerglide and the "I" should be a "1". Look close at the link, pic isn't the best.

http://www.chevelles.com/showroom/ccarney69/enginepadnumbers.jpg

Your question was "Has anyone seen an I in place of a 1 on a 402 block?". No, but 327 yes.

Ratbldr, yes mine is stamped TI103CTX...... The explanation I received from MORTEC was that the stamp sets usually only included a single '1' and that in my case the 'I' was used to fill in for the other '1'. Also, the '1' was an over used number (it could be used 13 days in a 31 day month)and that the tip would crack and or break, so the line mechanic would simply use an 'I' untill his punch was replaced.
NITRO

FYI

The letter I was used to indicate the month of Sept on cast engine parts.

Yes, on stamped date on engines, the I (i) and the number 1 are used interchangeably. Very common. If you think about it, they look identical, so its easy to mix them up.

So the block was cast on Sept 28, 1969 and was machined and assembled on Oct. 03, 1969. Then shipped to the assembly plant and may have made it into a car built the same month or next.

btw-Foundry and engine assembly were in the same plant complex, car assembly plant was not.

The POP has the T1003CTX, and transfer of warranty states the origional date car placed in service was 10-11-69, 8 days after the engine was assembled.

To back this up, the origional owner took it in for service on 11-10-69 for a "noisy lifter, shift lever loose and noisy, windshield wiper blades smear" with the car having 2,282 miles.

The I has always baffled me on the engine pad stamp, and so I kept the block out of the car, laying around for years for me to figure it out. I wasn't even sure it was the right block. I recently had it burned and blasted and all the grease and muck came off and the vin was discovered faintly stamped above the oil filter.

Thanks for your help guys!