The Yukon magnetic fill plug is M20 x 1.5 thread size and is intended for a range of GM differential housings including 8.6in, 9.5in, 9.76in, 14T and 11.5in units. The magnetic plug captures ferrous debris while sealing the fill port. Yukon supplies a full line of small differential parts and this plug is sized to match common GM axle applications listed in the product details.
Yukon Gear Magnetic Fill Plug 20x1.5 Thread