driveshaft splines

[wibilly]

i'm new to 4wd,s i just got 2 a 71 choped frame 3/4 ton and a 72 1/2 lwb was just wondering if the drive shaft splines are rebuildable or if driveline shop just welds new spline on shaft and you get a new yoke and what might a repair like this cost and how much slop is to much both front and rear have slop i got a new front one with the trucks but it's to short for the short box have not compaired it to long box yet the both have 205 / 350 combos