These I believe are the OEM specs, meaning grade 8 although aftermarket kits sell grade 5, like Savvy and JKS.
I dont know if these companies choose grade 5 because it is less expensive or if they do the job and grade 8 is overkill.
Grille Mount & Rear Body Mount Bolt;
5 Required;
7/16″-14 x 2-3/4″ Flanged Grade 8 Bolt.
Front Body Mount Bolt;
6 Required;
1/2″-13 x 3-3/4″ Flanged Grade 8 Bolt.
From the McMaster Carr Catalog (web). While not flanged, a washer under the head will accomplish the same thing; a distribution of clamping force. You can always cut the extra off with a wafer wheel and/or shim with washers if too long. You may find the extra length will fit.
| 3" | Fully Threaded | __ | Coarse | 5/8" | 19/64" | 150,000 | ASME B18.2.1, SAE J429 | 1 | 92620A685 | 12.26 |
| 3" | Partially Threaded | 1 1/8" | Coarse | 5/8" | 19/64" | 150,000 | ASME B18.2.1, SAE J429 | 10 | 91257A681 | 9.76 |


