Need Help with rear u-joint / u joint retainers

[my67chevytruck]

Hello,

We installed a '72 front member , and rear axle on my son's '67 in which we are running a 350/350. The parts truck was a '72 LWB 402/400 with a 2-piece drive shaft.

I went to oreilly and got some ujoints for a 1972 c10 one piece drive shaft 350/350 . The rear ujoint is not wide enough to fill up the ujoint space in the rear. I also picked up some ujoint retainers for a ;72, which dont fit either.

My question is should i get ujoints for a '72 402/400 for the rear? and a '72 350 350 for the front. also the rear seems to have threaded holes, did a '72 402/400 use the horse shoe type ujoint retainers or a different type?

Thanks for any help or suggestions !