Unless you need the box rebuild, do the drilling and tapping yourself. You can do the assist for less than $500. That's without being frugal. Worse case, you fuck up the box and already have the ram and hoses for the PSC box. The assist makes a night and day difference with the 37's.
2010 JKU. 3.5 RK Flex, 37" Nitto Trail Grappler MT on Pro Comp 7005's. Poly Drag link, Fusion 4x4 Tie Rod, DIY Hydro Assist, Ultimate Dana 44 Front, Rubi 44 Rear. Ten Factory Chromoly Axles, EVO RockStar Skids 5.13's, Poison Spyder Brawler Lite Bumper with Warn HS9500i, EVO rear D-ring mounts, VKS Prerunner Sliders, Synergy Cage