I was told 89 up is long style and earlier is short.
you wnt have a driveshaft lenght difference, but a u joint difference, short shaft and yoke use a different size cap than the long.
I bought everything except the slinger at Randys and the driveshaft bolted right up, caps were the same. Both sizes are available according to Randys.
I went through the different u-joint thing when replacing the yoke on my ZF. The F350 with DRW/crew cab long bed used the bigger u-joint, everything else below that used the smaller joint (reg cab, SRW, 250, 150, etc.). I have to make sure the parts guys go all the way to that last one on the list when I buy u-joints.
I have a nice brand new yoke for a ZF sitting on my desk for the smaller joint to remind me of that little detail.