Try looking on Honda Parts Now... enter details about your car (year/trim), see if you can find the stock sway bar and see if it shows the bolt that you need.
I think the bolt you are looking for is #18 in screen capture attached. Not that expensive if you want to get it from dealership P/N 90183-TVA-A00 - Genuine Honda Bolt, Flange (10X74) View attachment 8916
You hadn't mentioned that it was the rear bar (& I didn't ask/confirm which it was... oops 🙂). If you got #19 P/N Honda 90121-TBA-A00 Bolt,Flange 8X16 that looks like it's the right one.I ordered some random bolts and nuts for the rear sway bar (I think I accidentally left that out that it's the rear sway bar), I decided if I was going to buy it I was only gonna do it once but I bought the #19 and some other one in that general area
We will see when it comes in I used hondapartsnow Thank you for the inputs!
Shoot I had no idea because I didn't install it I also never really looked into the box after the install. Maybe I'll go back in the box and see what I'm missing. Is the bracket different then what you have. Because the OEM bolt I ordered is installed with some thread locker and it still squeaks. I have also noticed the grease area because I did see some videos.That appears to be the Eibach sway bar. I have installed on my 2020 2.0T. I can confirm it comes with a more robust thicker bracket than stock. This requires a longer bolt that came with the Eibach kit. I also see the middle threaded section is missing the grease fitting that allows owners to pump grease into the joint over time. That lack of grease could cause significant squeaks by itself, let alone the missing mounting bolt. Maybe contact Eibach and see if they will sell the grease fitting and hardware bolt by itself.
Hope this helps.