The speed sensor and splines are two completely different issues.
To remove the rusted in speed sensor the hub has to be removed and the sensor then pounded out from the inside. The spline condition will be observable during hub removal.
I did the 10% underdrive on my 2002 and it made all the difference in the world driving in mountains, in the east anyway. RPM`s increased by only 400 and no change in fuel milage. My loaded weight is 7600 lbs.
Now I can make it up about 3/4 of...
Check your front axle splines and drive flanges. Sounds like one or both axles splines are stripped.
Spinning axle splines would produce the sounds you are hearing and trigger the lights you are seeing.
Correct, they are studs that are screwed in. You should be able to remove the old ones from the old hub by locking two nuts together on the studs and wrenching them loose with the wrench on the inner one.
UPDATE: scroll down to post #7
Found myself with a cross threaded lug nut today. I knew it wasn’t coming off, so I just hauled on it until it broke. Here is how to fix that:
1. Toss out and replace lug nut
2. Remove lug stud, press in new one...