I have an 04 2500HD with the lly and the Allison transmission with 27,000 miles. I know the diesel is covered for 5 years or 100,000 miles. I was looking for some advice on whether the dealers extened warranty is worth the money and what it might cost.

I think the GMPP is worth it. Now a days "minor" repairs can cost "major" dinero. Also, the GMPP is transferable, and/or refundable when you sell/trade.