Honestly, I'm not sure if it is needed for the E53. I was able to do the front diff, rear diff, and transfer case with the tools I had before. I have not done the trans fluid yet so not sure on that. I can say that it will be useful on the E53 (or any vehicle with 14mm hex plugs) if not required. It allows you to use a crescent wrench/ratcheting wrench rather than just a ratchet but does also allow for the use of a ratchet if there is clearance. Really handy to have in the tool box. IMHO

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)