You can send your box out to Red-Head for a rebuild
https://www.redheadsteeringgears.com/. That's what I would do. These guys do quality work and are known around this forum as being one of the best. You can have them upgrade the box to a faster ratio as well.
For the ram assist, Corvettes and a couple other cars used them as well back in the day. Here's a great thread on rebuilding the ram assist if you need to go that route:
http://67-72chevytrucks.com/vboard/s...d.php?t=253657