Stock driveshaft works just fine. You'll need a conversion u-joint is all. You gotta make sure the 14 bolt you get is from the same series as your rig. You have a '97, so you need a axle from a 92 through 98 Suburban--maybe some '99s?--or a '88 through '98 Pickup. The ones out of newer or older rigs will not bolt up. They could be modded I'm sure, but that's a ton of money. The nice thing about the suburban is it has the right combination valve as well. But if you're going disc/disc then you don't want that combination valve anyway. The pickup can be a light 3/4 ton or a heavy half ton. If it is listed as 7200 GVWR it should have the 14 bolt SF axle. Also, you have to get the axle out of a 4WD. the 2WD version will not bolt up to your rig. The spring perches are about 5" too narrow on the 2WD. Measure the rear end from wheel mating surface to wheel mating surface. (The outside of the drum where the wheel mates up against.) You need to see 67". It might even be 67.5"? Doesn't matter as long as it's very close to 67" if you see 65" or less you have the wrong--2WD--rear end.
Around here--Portland, Oregon--these rear ends are pretty cheap compared to what I've read about the northeast. I picked up a good solid one for $200. It had an open diff, but I didn't care as I wanted to put in a trutrac anyway. The G80 ones go for about $400, and I found some that were good but with a bad G80 mechanism for $150. Every single G80 unit I opened up to look at had problems. It's got this gear ring with tiny teeth--looks like it belongs in a clock, not a diff. Every single one had many of those tiny teeth broken off. I'd never even consider a G80 again after all the bad ones I saw.
Do remember that you want to get the upper and lower U-bolt plates. They are different for the 14 bolt SF. Without those plates you'll be spending another $100 for mounting hardware. The guy pulling the axle for me just tossed them in for free. What's weird is that GM lists two part numbers for the lower plates, one for left and one for Right. I studied those damn things for hours and could not find a difference between the left and the right. I marked them L and R anyway and mounted them appropriately. Better to be safe...
I've not looked into the rear disc, so I can't help you there. Just remember you'll want a Disc/Disc Master cylinder and combination valve. Also, make sure you have good balance front to rear. Your rear brakes need to be less powerful than the fronts. If your rears lock up before your fronts you could spin during heavy breaking. The best way to balance your breaks is to match components with a factory setup. If you put on rear disc, get the same front disc, master cylinder and combination valve setup that went with the rears. Possibly even the ABS... You need to find out if the ABS unit does any proportioning or if it just does the ABS function. The later years of the OBS trucks have the combo valve bolted right to the ABS, but the valve can be swapped.
If you don't clone a factory setup then you really need to have someone that really knows their shit help you setup your brakes. That's beyond me which is why I cloned a factory setup off of the same body vehicle as mine.
For the trutrac, just google Eaton and get the part number off of their website. I forget the part number, but I got the diff from Summit. They didn't have the best price, but they matched the best price I could find online.
