I am in the same boat with a 98-GC 5.9 4x4 with front shaft MIA.
it has the CV on the axle end but a regular double u-joint on the xfer side.
I see a few of them with CV on both ends in those newer ones like you have.
take a look at both yokes to see what it needs.
I see replacements on e-bay in the 400-500 price range. but can find anything on how long or how to measure.
cant find it with only one cv end either?? I find the replacement CV but no shafts.
so you say they measure the tube and not the spline ends?
I look into the proshaft seller.