Guess you mean the wiring harness where is goes through the firewall.
So, no I don't know where to get the oval shaped one where the major bundle of wires goes through.
I am going to slice through mine at the bottom and hopefully put it back.
Some of the others that are like plugs (bolt access for hood latch) you can measure and find in parts diagrams for other models.
I found the ones mentioned in E28 parts.
Some others in E24 and maybe some in the 2002 or E21.
A place called Nostalgic Air has some general grommets that might be helpful.
Gary