2004 Chevy 3500 Plow Salt truck

2004 Chevrolet dump truck, has boss plow mount and wiring just add your own plow. Has a buyers saltdogg electric undertailgate salt spreader. The electric salt spreader needs an auger motor and gearbox when I put the sales on last week it was locked up. The airbag light is on no idea why never been deployed. Check engine light has been on for years my mechanic has told it’s some sensor and not to worry about it. Rusty as it has been used as a salt truck for the past 8-9 years but very mechanically sound, if it needed replaced I had it done. Recently got new exhaust manifold. I got out of the industry and it hasn’t been used since last winter just occasionally driven around our parking lot.