Toqrque limit on Dmax LLY with 6 spd ZF

[Dan Herr]

I am abbout to order a 2500HD Duramax LLY. I would like to get the ZF manual transmission, but hate to be limited to the HP/torque limit of the old Dmax.
I understand that the ZF is heat limited - extended trailering up a long grade may overheat ZF at higher torque limit. As long as I don't do any heavy trailering, any thoughts on whether I should get the ZF and just reprogram the LLY to the higher Allison output levels?

[Chris N5CWM]

Does the ZF have PTO covers on it? If it does then you're in luck. FAST COOLERS (http://www.fastcoolers.com/fastcoolersindex.html) work great on the NV4500 and 5600 trans. You can add a temp probe and monitor the fluid temp too. Increases lube capacity also.
Then feel free to add your choice of power enhancing devices to the LLY! :D

[CPMac632]

You won't hurt the ZF with a little higher rated engine. Now the flywheel is a different story. The ZF does have pto covers so if you wanted you could add a cooler.

[ksevern]

It's been a while since I've been on the forum, so sorry for my ignorance, but what is an LLY?

[bluenote]

LLY is the RPO code for the 2nd generation Duramax engine that just started production.

310HP and 590 lb-ft of torque when paired with the Allison, same numbers as the LB7 (1st generation) with the ZF-6 manual, plus some other modifications to help with servicing and power output.

[txguppy]

What's the RPO code?

[Colorado Kid]

RPO = Regular Production Order

Its the ordering and "glovebox" code for any particular equipment.

Some examples:
G80 is the RPO code for the locking rear axel.
M74 is the Allison Automatic
ML6 = ZF manual transmission
LLY = "new" Duramax 6600
LB7 = "old" Duramax 6600
L18 = 8.1L V-8
Z82 = Trailering Equipment Package
C6W = 9200# Gross Vehicle Weight Rating
GT4 = 3.73 axle ratio
GT5 = 4.10 axle ratio
PYO = Forged Aluminum Wheels

Knowing this stuff makes me a truck nerd. :D