Hey Walmart I know................

Cool, your not worried this will shorten the life span of the new battery?
I was always told you shouldn't mix new and old batteries (but at today's cost, I can totally see why you would)

I wonder what makes your truck start so well I'm winter?

My plow truck is a 6.0 diesel and a real pain to start when it's cold, or sits for a few days
Don't know. Might check into fuel pump issues.

It's an 01 24V with about 145K. Always started great. I have a "tune" about 1 step above stock, I don't even remember the box I use. Either stock or with the "tune" it has always started "instantly"