is there any way to know for sure if my truck has had the reflash or not? my dealer sais it has but i am still having problems and i don't believe them.

try this link GM vehicle calibration info (http://calid.gm.com/vci/VINEntryPre.do)
This will tell the most current SW available for your vehicle.

Then you will need a Tech 2 to compare your calibration numbers.

Had my computer reflahed the other day (8/12),,sm said that it was updated per si bullentin 1557897 . Could not find that # in reflash info,,,any info on this ???

isn't this on the invoice from the dealer??? I just had mine reflashed and on the ticket it says it was reflashed with PIP 3129B... I have had much trouble getting this done and also been told I had the latest code as well from other dealers.