engine to pump driveshaft is PTO shaft parts by caliper measurement. so I can make adjustments as needed there and make a new slip in the middle, and lock down those loose splines. Probably just add a couple set screws to it and tighten the dogshit out of them, and hopefully make a short square slip between the middle yokes. I hope I have enough length to do that well without getting fancy.
probably have to pull the engine to get at that shaft, and also to make running new lines easy.
Pulled the trigger on lines and fluid and a filter, so I am sticking about $500 into it. Only other known issue is a sloppy shutdown actuator on the injector pump. bushing and seal are shot and it's a diesel dripper. It definitely had electronic shutoff actuator originally, but that's a $300 list item which is probably why it got a mechanical linkage, and the added load of that linkage is probably what shot the bushing over time.