I know most just use the van OS, but here's an 01 L31 manual trans from a GMT-800 truck out of Mexico. I'm still on the hunt for an 02 to compare to the 02 van OS. I did see quite a bit of difference in the VE table when comparing this one to the 02 van tune file I have. I know the L31 in the GMT-800 trucks used the larger MAF sensor like the LS engines used, but I wouldn't think that would make that big of a flow difference, especially considering the MAF scaling is different in each tune to match the MAF sensor used. Or it could be the newer intake just flows that much more(in which case I'm going to put one in my TAHOE).

2001 L31 manual.ctz