Jack, if you're dead set on. Auto trans, then the 4l80e and the 4l60e would work great with the 6.0. If not then grab an NV4500 or NV3500 which are manual. I got my 6.0 shipped from Arizona to Reno for under $1200. You could easily shop around and find a local wreck and get both the motor and transmission in addition to all the accessories and everything for around that price. The 6.0 I have is a 2004, and Justins 5.3 is a 2006. The things to look for in your case would be a GM gen III engine. The 6.0 is either an LQ4 or LQ9. The 4 is basically lower compression and a bit less power, but can run on any pump gas, where the 9 is higher impression and a few more horses, but runs only on premium. These are definitely going to be the ticket for just hopping in and going. They've got plenty of nice features that make them run better than their predecessors and if you are only using them for plowing or offroad and dont need to smog them, then you can ditch a lot of the pollution controls and make them even simpler and more powerful. I already have HPtuners which you would need to unlock the vehicle anti theft system with and calibrate everything. You would only have to pay for the credits they charge to access your engine and trans. Do some
Reading and I think you'll find that the newer systems are actually far more reliable than the older ones. Plus you can get parts for about the same if you're willing to shop a bit.