On my 98' Silverado I am replacing the hub assembly and took the old one out of the knuckle and need to know if after cleaning out the knuckle/hub opening do I leave it clean or put grease in it before installing the new hub? Also, should I replace the seal on the back of the knuckle where the axle comes through, or how do I even tell if its no good? Thanks for any info!

 

When I did mine I just cleaned off the spindle and covered it in grease, then just put it back together.

There may be a difference between 1500 and 2500 hubs though