OK to lift a truck with the NP246 T-case?

[crashandburn]

Separate thread because this is a big enough deal to be a deal breaker. I just noticed that the diesel burb that I am about to buy has the Autotrac NP246 transfer case. The Pro Comp 6" lift says not to use it with this case. After some searching it looks like if I stick with a 4" I am ok, or if I go 6" I am ok as long as I lengthen the front driveshaft.
Can anyone confirm this?

 

[K85 Octane]

I can't see one lift being ok over another. 4" vs 6", I don't see the difference. Either one may need BOTH driveshafts extended. But why would that stop anyone from putting a lift on, or considering one T-case usable and another not. dunno I guess I'd have to see the np246, but if a 4" is ok....