Does your truck have a 1 or 2 piece driveshaft currently? If it's got a 2-piece, just install the Brownie in place of the carrier bearing, and slightly lower than the main trans centerline so the U joints flex a little. An inch or two difference in height should be sufficient. Try to avoid getting any of the U joints into an extreme amount of flex, but do use enough angle that the shafts aren't running in an exactly straight line with each other. I believe there's a Dana/Spicer website somewhere that has setup instructions for auxiliary transmissions and multi-piece drivelines.
Jerry
