The correct metric size of the bolts used at the rear of the front oil cooler cover are M6 x 1.25. The captive fastener is a M6 x 1.25 Tab Base Weld Tee-Nut with 2 Projections. See here https://pbase.com/9146gt/image/141450343

The M6 Tab Base Weld Tee-Nuts were sourced at Stoddard https://pbase.com/9146gt/image/159800560 and they also have the M8 for the Alloy Hood Pins. The M8 Tee-nuts Stoddard has are not 100% correct for the GT application as those only have two https://pbase.com/9146gt/image/159800561/original projections, not four https://pbase.com/9146gt/image/138989533