help w/ Yukon axles & thrust spacers

the spacers are in place, the thought of them having fell out is what made me pull the pig today. i figured that a little chunk of metal loose in the diff might not be good.

the yoke swap is because i think that i'm going to get a new drive shaft. i cut the old one a little too long (less than 1 inch) and i'm not sure it's salvageable. on a new shaft the difference between large and small is $10, i have both pinion yokes so i figured that i would go large. i need a new pinion seal anyway.

i understand that the 70's a body 340 cars came with small u-joints, are the large joints significantly stronger? or is it just perception. what are most people running?