Our differential covers use a 9/16 allen wrench to tighten the fill plug. Instead of buying one you could just make your own out of a 3/8 bolt with two nuts because the nuts for a 3/8″ bolt are 9/16 OD. Its a tool you don't need to often but it is something you can carry easily enough and make from scrap parts around the garage..
Current Fulfillment Times: UPS - 10 Business Days. USPS - 3 Business Days.