forth gear syncronizer is going bad I think. makes a little grind when going in. on 1998 Chevrolet 3500 Pickup

it seems to grind less when you down shift. it stays in gear no problem.all other gears go in easy.How expensive is it to correct this.also if I continue to drive it how much damage am I causing. thanks o.d.

Asked by for the 1998 Chevrolet 3500 Pickup