Theres no real cheap or easy way, unless you luck up on a deal. A thing you have to keep into consideration is length. A full size trucks drivetrain is quite long. That equals a short driveshaft. You could go Nv3500 out of an s10 but they are very long, as they have a non removable bell housing. Could also get a nv4500 but they are very expense, even used, I think the last one I saw on CL was like $800, without a transfer. A SM456 is a good option but thats a 4speed, then you'll need an adapter to get a driver side drop transfer. Unless you find one out a 88 up, which is fairly rare. Like Cruiser mentioned, the NV3550 is a good choice. But quite honestly for money and the ease of doing it an automatic is a great way to go, whether it be a th350 th400, or 700r.