So I picked up this HPI Diff brace for my C5 and found the bolt holes to be countersunk. Then I noticed you can't get a socket in the hole due to the holes not being much bigger than the bolt heads, and there is only a thin bit of the supplied washer that makes contact with the surface at the top of the holes. This had me concerned so I created some bushings to fill the hole that are snug on the bolt and in the brace. I used carbon filament in my 3d printer. Here's a link to the STL file I created for this.

HPI_inserts.stl

My car is apart, and I'm waiting on my built Diff to come in, so this isn't fully tested at this time, but I did check the fitment against my stock 2000 diff, and it fits perfectly. I did size this so that you will need to tighten the bolts before the bushings will sit all the way down flush in the holes

, and when you do it will allow the washer to evenly contact the brace body and bushing.

I have also see some videos where people had to drill out the hole just a bit in order to get the bolts to align with their diff. I did not have to do this with my stock 2000 diff.



PM me if you cant get the link to work and we can find another way to get you a copy of the file. STL format is not supported for posting.

 

I took a router and set the bit depth to the bottom and just hogged it out a bit. If I did it again, I'd just cut out the sides of the hole so you can get a ratcheting wrench on.

 

 

Could always just replace the bolt with an allen head. Or buy a better mount and not the cheap copy. I had the Pfadt on mine (bought it from them as blemished so I paid considerably less)... I just switched to the AMT double barrel mount and it is a solid piece.