In your opinion were any of LLY, LLY/LBZ, LMM, LML first year lemons?
Everyone including GM will acknowledge the were/are emission issues with LML (the '11's were are recalled to address this -- and we still debate about the success.
LB7 had well documented fuel system issues.
LLY (04.5 -05 version) is/was known for the potential to overheat in certain situations.
I'd don't get the connection you're trying to make between LB7 and L5P.
2011 GMC 2500 LML CCSB 4x4 SLT
sold 2010 GMC 2500 LMM CCSB 4x4 SLT
sold 2004.5 GMC 2500 LLY ECLB 4x4 SLE