I have a '98 Chevy z71 4x4 and Recently it started making a strange noise, almost like a light grinding, from underneath while driving. A few days later at night i noticed faint light underneath the truck reflecting off the road. Looked like sparks or something. The stearing jerked a little a time or two but it ran fine for another 15 miles with no issue. I haven't driven it since but I have no clue and dont want to cause a costly repair by driving it any more. Any Ideas?

 

I would try jacking that wheel up and checking the wheel bearing, Idk about the light you saw,

 

Jack it up and rotate each wheel and listen for any noise and ID it. Sparks etc are usually associated with brakes or some metal contact with the wheel or other rotating device. How did the brakes feel when applied? Which way did the steering jerk?