This steel speed nut, clip nut or U-nut, by Foxbody Performance is the correct size (M6) for 86 to 93 original fender bolts.  However, if you are upgrading your fender bolts to an M6 size, these...

See the kit descriptions below and select the preferred kit before ordering. These M6 & M8 stainless steel bolts with polished stainless steel washers will look awesome in your engine bay!  Brought to you by Foxbody...