I know it is hard for some to grasp, but it's not always about the money. If this is what your DH wants to do, and he really likes the truck with the exception of the standard, I say do it! As the link that is posted above demonstrates, it has been done, and can be done in the future. If it will not be a financial burden and you don't expect to get your money back, then why not? Sometimes it's nice to have something custom that no one else has, and a cummins/Allison would be quite rare.
With all that being said, how about some pictures of your custom truck, bet I am not the only one here that likes to see custom trucks.
