Source for BSF cup square coach bolts?

Does anybody on this group know of a supplier of cup square coach bolts in 3/16th BSF? I need a couple of these to repair the airconditioning fans in my car. Each fan has two 3 inch bolts, and the square behind the head seats in a square hole in the casing, which is about 3/16th, or roughly 4.5mm. The other half of the casing is then secured by a nut on the end of the bolt.
It seems impossible to get coach bolts in anything less than M6 thread, which is of course far too long.
I could possible make do with a plain hex head bolt, but would like to replace the original bolts.
Is anybody able to help me out here?
thanks,
Michael
-- remove "_spamwitheggs" for e-mail.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.