I have 6" lift on mine and the front driveshaft angle was (and still is) a nightmare. I destroyed several double cardan joints and mine is no mall crawler, it would see serious trail twist. The SM465 4-speed is shorter than the TH350 so that contributed to my problems I think. I ended up putting a yoke from a '76 NP203 on the NP205 front output and made a custom box steel front driveshaft, and STILL had to modify the crossmember, as well as shave some material off the t-case yoke nut and driveshaft yoke lol. I took this a step further by putting a 32-spline front output shaft from a F*rd NP205 in my t-case, which would allow me to run a 1350 or 1410 yoke for greater angle. I also was told a tip I want to try one day where you can use a Dodge 2500 front driveshaft from a mid-2000's truck and have it cut to fit. The double cardan joint has 1350 u-joints and provides greater than 30 degree running angle, unlike our stocker with 3R joints and less than 25 degree running angle.
The rear I lifted using a shackle flip and that brought its own set of problems. A shackle flip causes the rear axle to rotate the pinion up and moves the axle forward a little. So I had to use zero rate add-a-leafs to move it back about an inch, and since I went with a 14 bolt rear (on a half-ton) I had to have the driveshaft lengthened (the 14-bolt's pinion is a couple inches shorter than a 12-bolt).
You're also going to need longer brake lines front and rear, and you'll have to address your steering geometry between the steering box and axle. Most people get a raised steering arm and/or lowered pitman arm. You basically want your drag link parallel with the road. If it is angled you'll have more bump-steer, reduced left steering radius, and if you twist it up on the trail you will have NO left hand steering whatsoever. (Ask me how I know this hahah) I had to go with a crossover steering kit, which involved swapping out the steering box for a 2WD box. Since I had a Dana 60 front axle, the kit came with a passenger side kingpin cap/steering arm and made hooking up the drag link easy. On a 10-bolt or Dana 44 you have to get a whole steering knuckle for the passenger side that can accept the drag link (more expense). I honestly think I would have been happier if I kept it at 4" lift but you pay a heavy price when learning what works on your particular truck and what don't, all because I wanted to run 38" tires.
