I know seems like a stupid question, but I was curious as to what the stocker system looked like on a 03.

I think I understand your question so here goes. A stock system will contain a downpipe and connection just under and behind the front right wheel where the downpipe and exhaust will connect. Some will have a cat, depending on sales location of the truck and then a stock 3.5 inch exhaust all the way out the back. Not sure if this is the answer you are looking for but that is the best description I can give you. Hope that helps...

Thats pretty much what I was trying ti finger out.I just happened to be under mine today lookin around, and noticed no cat , so I was a little puzzled was all.Thanks.

Duramax had no cat until the LLY came out.. UNLESS it was a CA emissions truck or related. More than likely yours came without one which means you have none of the EGR issues and snags that we have to go through.

yup yup, no cat installed.

Heres the picture of the one off my LLY the cat on the LLY and LB7 look the same in the out side.
http://img.photobucket.com/albums/v68/mr.zombie/exhaust.jpg

and yes that is my bedroom):h . and yes that is my stock ally cluctched above the exhaust! Its decorated with car parts.