Since I have one of these in my possession for the next couple of days I thought I would document the dimensions . They are NLA.
Reference link.
https://www.sl113.org/forums/index.php?topic=11922.0Here are pictures and measurements just in case you need to make one.
Intermediate Horn Bracket (NLA)
Driver Side Only
Used if car has power steering
230 SL & 250 SL (Maybe very very early 280)
Driver side should have welded bracket to chassis, this immediate horn bracket,
laminated isolation bracket, then horn
Please let me know if I need to add more information or correct anything.