Ok, So i hear all this stuff about allison only being able to 80rwhp and there just slapping that label on to all the engine codes. Considering allisons are the same except 6spd wouldnt it make sense that a LMM should only be able to hold the least amount of power since it has the most power already and LB7 should be able to hold the most? Say 100 crank for LB7 and that would be the equivilant to 35hp on LMM...

The 6 speed ally has better holding power from the factory thats why it only take the transgo jr in the suncoast kits rather than the whole transgo.

Agreed:)

Ok, So i hear all this stuff about allison only being able to 80rwhp and there just slapping that label on to all the engine codes. Considering allisons are the same except 6spd wouldnt it make sense that a LMM should only be able to hold the least amount of power since it has the most power already and LB7 should be able to hold the most? Say 100 crank for LB7 and that would be the equivilant to 35hp on LMM...

Its all about torque. The C2 clutch used in 5th (and 6th) gears had less capacity on the 5 speed version used in 2001-2005 models. Around 750 ft-lbs. If you start with a 2001 LB7 making 520 lb-ft you've got more room to make improvement before getting into trouble than you do on later engines with higher ratings.

For 2006, the C2 clutch was redesigned to give it 30% more holding power. This put some margin back in with the higher rated engines.

Horsepower just isn't a good measure for trans capacity because its Torque X Speed. You can get higher power numbers by turning faster, but many slips happen at lower RPMs where the diesel can make strong torque but the trans is at lower main pressure. Watch it lugging back into 2nd in T/H with added power... The Duramax can make serious torque at 1200 RPM.

Ok, so your saying like no more then 750 crank tq?

Put no more than 700-750 ft-lbs crank torque to it in 5th for a 5 speed (2001-2005) version unless you've made clutch mods.

Also, the torque converter clutch isn't far behind for other ranges. Its in the 800-900 ft lbs range.