I am not sure if this will help anyone, but I found a 98 Ranger from California here in Ohio and I rebuilt the entire front end. The only thing I used that wasn't brand new was the front differential axle housing. I replaced all the internals, from the gears all the way out to the manual locking hubs which I was forced to use because I could not find an original set of hubs. Both my hubs came within 100 miles of driving, along with the classic vibration that comes and goes every time you hit a bump. The manual hubs are heavier than the originals and need to be secured somehow. I have found a few solutions were people used glue, silicone, or CV joint metal zip ties.
What I have found, worked best for me was to very carefully bend the plastic tabs up and away from the center of the hub so they lock in stronger. I have seen people apply heat for this but you have to be very careful as it is extremely easy to melt the plastic. Unfortunately I cannot find any better solution, as I fear this will not fix the issue permanently either, only time will tell. Good luck, please let me know if anyone finds a better solution. Thanks all.