A Detroit Locker can be had a lot cheaper than a selectable locker. Think I paid about $550 for mine. Installing would only require a backlash and pattern check, not full gear set up.
95 Crew,owner converted to 4x,PS IC,Baumann TCS
95 Lightning,Dropped,Notched,MiniTubbed,Turbocharged,Holley HP,owner built/billet E4OD,US Shift