spool weight difference

No, what we meant was: do I have to remove the ring gear to slip a lock-rite into an open Ford nine inch carrier. My buddy would surely have known......
If I have to pull it all apart for a lock-rite, I might as well pit a spool in it......
I am almost 100% certain no ring gear removal required. It's all gear dependent. If the ring gear is pretty thick (a low gear set like a 4.10) it MIGHT have to come off. But that's no big deal. All you'd have to do is reset the backlash. A drunk blind man on drugs can do that. No offense to drunk blind men on drugs.