Driveshafts are (obviously) the round shafts that allow for power to transfer to your front and rear axles. They play a very important role in any 4wd, and of course are especially important with your SOA. There is not a whole lot to worry about except that if you don't get it right, you will have some vibration.
One of the main reasons you point your pinions up is for the sake of your driveshafts. I do not have a whole lot of experience with spring over conversions on 40ís and other short wheel base (SWB) trucks, but on a long wheel base (LWB) truck (a 55, 60, 45,etc), at least in the rear, if you rotate your pinion up (there is no real reason not to), you should be fine reusing your driveshaft. It is common knowledge that if your axle angle and your transfer case output angles are not identical, then you will have some vibration. This is true in some cases but for some reason in an FJ60, when you rotate your rear pinion up and weld it up that way, you do not get rear driveshaft vibration.
However, if you do have fairly larger differences in pinion angle to transfer case output angle, the common cure is to use a CV joint. CV joints are abundant in all sorts of vehicles. I am currently running one from a '87 1/2 ton Dodge pickup in the rear of my cruiser, however there are lots of good models. If you are using your OEM Toyota transfer case and axles, an excellent CV joint to use is a mini truck or early FJ60 (same CV joint) mated into your Toyota shaft. All Toyotas use a 2.5" driveshaft, and there are several Spicer and Detroit drivshafts that can be mated into a Toyota shaft. Regardless, if you need a driveshaft it will have to be custom.
One neat little trick for the fronts of 40ís, 55ís, and 60ís, is that because all Cruisers used the same diameter shaft tube, and at least have the same size ďpilotĒ (the ring in the middle of the flange on your driveshafts, pinion flanges, and t-case flanges), you can use the mini truck.early FJ60 CV (which is almost identical to that of an earlier 60 series) to extend your driveshaft and get the benefit of a CV joint in your shaft.
On a late 60 spring over, a CV joint from an earlier model, welded into your later shaft, is the perfect length needed to bolt it in. You will not have to notch your cross member, and you will not need a long slip joint in this scenario, unless you are building a 60 with extreme articulation.
CV joints are actually useful items that allow you to achieve less vibration and work through some tricky spots with driveshafts. There are custom driveshaft shops in just about every major city in the US. Usually it is a lot cheaper to have them shortened than to have them extended.
Anyone with good fabrication
skills can whip up a driveshaft, but the key to driveshaft shops is they
have balancing capabilities. On a trail rig, one thing you can get
away with is making your own front driveshaft, as long as you have hubs
that unlock. But it still isnít recommended. In the rear, it
is a must that you have your driveshaft balanced at a professional shop,
if not completely built there. There are several companies that make
high angle drivelines, for example, High Angle Driveline (www.highangledriveline.com).
I personally do not think they are necessary in most applications except
for serious off roaders with high articulation suspensions. Plus,
aftermarket CVs are usually pretty expensive. I recommend using a
good, cheap, used CV when necessary, and the Toyota CV joints are great.