Bowtiesr4me, if you have a friend or neighbor with a lathe and welder you can modify a stock driveshaft with the correct yokes to fit your length. All that is required to shorten a driveshaft is to put it in a lathe and machine out one of the yoke welds and chop the tube to the desired length creating a square end. Then the yoke is inserted into the stub and rewelded and the job is done.

I've only done a couple of those and neither one vibrated. If it does vibrate a driveline shop can balance it. It's no more complicated than balancing a wheel. A small weight like a washer is tack welded on.

Ray