Topic: Late 66 SJ Fender to fender apron bolts

[21.04]

I'm looking inspecting the hardware under the hood on my 7/1/66 projected build SJ hi-po Conv. The original owner changed a few things under the hood that required hardware, so I'm questioning wether or not these fender bolts on the car now were a style found on late 66 SJ cars?  They all have the "M" same markings.   I couldn't see these particular marked bolt heads on any of the photos in the unrestored section.  Most I've found are SEMS marked heads.

[Bob Gaines]

I'm looking inspecting the hardware under the hood on my 7/1/66 projected build SJ hi-po Conv. The original owner changed a few things under the hood that required hardware, so I'm questioning wether or not these fender bolts on the car now were a style found on late 66 SJ cars?  They all have the "M" same markings.   I couldn't see these particular marked bolt heads on any of the photos in the unrestored section.  Most I've found are SEMS marked heads.

The wrong marking . I have seen that bolt as a older sourced aftermarket bolt for restorations.Yes the SEMS marked bolt with (spinning washer) is what you need.

[J_Speegle]

Agree that the ones you have are replacements

For a July San Jose built Mustangs you would find either the hash mark or SEMS IMO. Both were used during that month and you can even find a mix on some cars in the 6R223xxx-6R23xxxx production period. Best to go with one or the other just for the look and the fact that your replacing incorrect bolts with "correct" ones and you don't have any documentation that your car came with a mix of the two possible ones. Examples from the production period below

[21.04]

Perfect!  Thank you both.  I do see the hash mark bolts on the tops of the fender aprons and down the shock tower areas on my car.  I'll scrap the M marked bolts.