Engine block decoder

I have reason to believe that my engine is not the original that it may be from a 93-98 Grand Cherokee and took this image of the block number on a flat area between the distributor and A/C compressor the number is 71OM29 does anyone know of a decoder for this?





I found a post that said the casting numbers are on the drivers side of the block behind the power steering pump these are the only numbers I can find there.

 

I would guess the casting number you found is the day and year the block was cast. ie. the 299th day of 1987, 26 Oct 1987 if my calculation is correct. There should be another casting number for the block to indicate CID/Liters and casting variations of that. ie. 4.0L etc.

The 71OM29 should reference a portion of the VIN of the vehicle it was destined for when built. This was dictated by the government starting in the late 60's as a tool to prevent theft so if someone was stealing and stripping cars to resell parts, they could tell if the engine or other parts were from a stolen car.

My information is assuming the same logic holds today as did in the 60's and 70's and I see no reason it wouldn't.

This is where the term, "Matching Numbers" engine comes from.

Hope this helps.

 

I never thought about that with the 710M29 and I follow Dennis Collins on YT and that is something he always does, I will have to check my VIN

Thanks

 

Since 1987 was the first year of the 4.0 that would mean my block is the 199th block ever cast.