I have another 4Lo question. The '05 manual says that 4Lo may not engage when its too cold outside. Does anyone know how cold is too cold?

I don't expect to see anything below -10F or so where I live. But, maybe I should put it in 4Lo when that truck is warm, like after work, if I think I'll need it after a very cold night?

I think somewhere around where you read that in the manual it will also say something along the lines of letting it warm up or driving it a bit when it's really cold, and you should have no problem getting it to engage. You may just want to double check, but I think that I read that in there.

Yes, it does say that. I still wonder how cold it needs to be before there is a problem, though.

colder than the pour point of the lube you have in the Tcase.

Much colder than it gets around here.