66 c10 CPP collapsible steering shaft install questions

[Afirehawk1]

Starting to install this

3/4 inch DD intermediate shaft from CPP

1. How far does or should the center shaft slide? Total possible is 8.5 inches
2. On the u joint, one end (DD) has threaded studs with locking nuts. I am assuming the other end (slip on round) gets welded where i cut the existing shaft off?
3. I am also assuming the ujoint is what makes this collapsible?

Also thinking on 1 of the 2 studs. The one that sticks out further i could remove it; then drill DD shaft and actually have it pinned

On the intermediate shaft. The section in the middle is rubber. Assuming i would drill and pin in front of the rubber section that has a flat spot on the bar. 1 or 2 pins there?? Also thinking i could cut the DD shaft to length for adjustment; why i was asking how far the DD shaft slides forward

Anything i should be aware of before cutting my original shaft??

Thanks

Keith