Removing & Replacing Pickups in Gibson 335 style guitars or a Hollow Body guitar typically takes more work than it does on most other electric guitars.  All pots typically need to be dropped into the inside of the instrument in order to access the pickup leads that are attached to the Volume pots. The jack and any tail piece ground wire may also need to be released in order for there to be enough slack to manuver the volume pots into position to de solder the leads. Once the new pickup leads are soldered into place, All of the pots have to be fished back into position with out breaking or compromising any of the electronics leads.