[68PanelTruck]

I was doing a little work on my C-10 1968 Panel Truck and pulled the rear drums off and found that the axle seals were weeping a little. I unbolted the axle retainer on one side and pulled out the axle. When I did this the axle thrust thingy fell off way down in the axle tube. From doing research this thrust button is used in combination with the adjustable axle retainer to set the runout on the axles.
Question is, how do I put he thrust thing 29" down the axle tube into the ring and pinion carrier into the small hole where it sits? There is supposed to be one button on each side that join in the middle.

My truck is a 68 c10 with a 4 speed and a big block so it has a rare Dana Spicer Powerloc diff. I have both the shop manual and the overhaul manual and neither covers this in any detail. I do know that this is a really heavy duty diff and was also used in Hemi powered musclecars, Ford trucks and others but I can't find any info on how it goes back together after doing a simple job like a axle grease seal. I'll put some pics below. This is the trust button , flat side touches the end if the axle. The roll pin goes into the carrier and I'm guessing that the roll pin connects both thrust buttons together.