What do these numbers mean
 

I have a 91 C2500 Silverado, 5.7L automatic. I'm the original owner.
in July of 2009 I replaced the motor with a 5.7L Long-block, crate motor. this new motor has 28,192 miles on it.

The numbers on the right front of the block are: 1M0920
8G35

What do these numbers mean? Was this a "New" motor, or was it a remanufactured motor?

Thanks

You had the engine replaced.......Where did you buy it? What did they tell you it was? Do you have the paperwork from the job?

The original motor never was really all that good. It was prone to over-heating, poor oil pressure, etc. Finally it spun a rod bearing. My mechanic just happened to have a crate motor that someone ordered, but due to the crash of the economy, they couldn't pay for it. The new motor was purchased through a local Chevy dealership, I have the part number and serial number, but they don't come within a row of . . . . . the numbers on the block.
Ok, so my mechanic gets stuck with this motor, and says he'll put it in my truck at cost. i'm just getting nosey and would like to know what the block numbers mean.
The paperwork just gives the part # and serial#