s13 mid-driveshaft bolts?

[zerog]

I found that one of the bolts is missing from the middle u-joint on the driveshaft of my 92 s13. These are not hex-head bolts, they are shaped bolts that lock in place to allow you to tighten the nut with only 1 wrench. Anyone know where I can buy these, or a part number? Or a size so that I can replace the missing one with a regular hex bolt.

I did some searching but I'm only finding info for the bolts that connect to the differential.

Thanks!
https://i.imgur.com/1WAwZQi.png

[zerog]

I removed one of the 3 remaining bolts, this is what it looks like, you can see the head is shaped to hold the bolt in place and prevent it from spinning. I believe the size is M8 x 1.25, longer than 25mm but shorter than 30mm (I used a 30mm for replacement). The nut is 12mm.

https://i.imgur.com/G3oDPBO.jpg
https://i.imgur.com/NCh1F0F.jpg

This bolt with a flanged head would not fit due to the flange, so I cut part of it off with a Dremel to create a custom shaped bolt, it fit great.

https://i.imgur.com/2B3AOHO.jpg

I was not able to find a bolt at the hardware store in this size with threads on only half of the shaft like the original bolt unfortunately. Thinking about just replacing the 2 piece driveshaft with a 1 piece one.