u/DJHouseArrest

I just bought an old 2012 Outback and the rear lift gate doesn’t have the support cylinders/struts installed. The girl I bought it from bought some new struts but couldn’t find the hinge bolts to put them on. I looked online and I’m pretty sure I found the right part (901060013) which is an M6 x 20mm hex flange bolt. But it’s more for shipping than the part is worth, so I headed on over to the local hardware store and picked up some standard M6-1.0x29mm flange bolts. I tried just hand threading one of them in and they are not threading in for some reason, like the bolt is a little too big or something.
Is this some sort of proprietary bolt or something? Do I have the part information wrong? What am I missing here?