How difficult would this be to make?

It's just an adjuster. I want to use something like this for the Watt's bellcrank mount because just 1/8" of adjustment makes a rather significant change in the geometry.
The "teeth" would be 1/8" wide (from point to point) and 1/8" deep. The slot would be 4" x  3/4". The teeth would cover an area of 1 1/2" wide x 4 3/4" tall. The overall plate would be 5 1/4" wide x 4 3/4" tall. I figure start with 3/8 with the edges milled to 1/4" thick (1/4 strip on each side) which would live 1/8" step to cut the teeth in. Would also need a piece 1 1/2" square with matching teeth cut and a 3/4" hole.
It's the piece the panhard mounts to in the first pic and the coilover mounts to in the second.





Anyone have access to a mill 

I wish I had access to a milll.

Not very hard if you have a credit card or Paypal account.   Check out what you're looking for here or on page 8 here.

Later, Doug

Thanks Doug.
I was searching serrated panhard mount, serrated plate all kinds of crap. The only ones I came up with was 5/8.

Some really COOL stuff on both of those sites!

Some really COOL stuff on both of those sites!

Yeah, there are other sites like those but those are two of the better ones.

Later, Doug