f250 solid axle

Ok guys. I know there is info all over the web on this but I keep finding scattered and conflicting info. Here's the deal: I have a 1997 F250 HD 4x4 7.3 powerstroke (older square body). Axle code on door sticker is 39 which = 3.55. I want to swap out the TTB with a solid axle, so I'm...