BUY NEW GEARS.....esp. at 4.88. The D30's pinion is Cute, but seems to work fairly well. The new gears will set up better and run quieter than a used set. You also then know how much the front has been stressed and can do your D30 inspection accordingly.
Assuming you're already running a stock 297 jointed axle in the D30, the alloy shafts are a great idea. At the very least, have a replacement set of long side and short side axles available and assembled with unit bearings (15 min. trail fix--wheel, caliper and 3 12mm-12 point bolts and you're in business) and at least a set of upper and lower ball joints (a little longer than the aforementioned trail fix, but still nice to have a set of ball joints---can be fixed with a BFH, but ball joint press is a nice trail tool---let me know if you find a cheap one--I'm looking).
More D30: I'm fairly equipped with 297 stock shafts right now and snap ringed the set I'm running with 760 joints. I'll run them this season and see how long they last, but I expect to replace them for next year. Kind of the price of running a stock shaft in the D30........The alloys are sweet if you want to spend the money.
My D44 seems to be handling the stress very well, but I'm looking for a spare set of shafts (I have a 'long side one'--there's only 1/4"-1/8" of difference in length) just in case. I think you could get by for getting out with just a shorter side D44 spare. The splines wouldn't be ideally engaged, but they'll work to get you back to your tow rig....