When I bought the indexer Arc didn't have the tail stock in store, they got them in a few weeks ago so I got one.

I unpacked it the other day and checked it out and this is what I found.

It was a good 8 mill under the centre line of the indexer, so gave Arc a ring and they were very apologetic and ask me to return it and they would refund me, there was no argument from them. So I went to pack it up and then I remembered, I'd added this to the bottom of the indexer.

and double

With great embaresment I rang them back and explained my mistake.
Everything lined up fine on the mill.
So decided to fix an alignment bar and to drill some clamp holes to the tail stop.
First job mark up the centre line I used the same method as i used on the indexer.

Then set it up on the mill and clocked it up so the bore was square.

And skimmed a datum edge.

Then with a clamp bar through the bore clocked the datum edge up square. Ran a clock over the flat face and it was fairly level good enough for function.
Then using the scribed centre lines drill and tapped M6 for the register bar, and drilled 10mm for clamp bolts.

I made the register bar again a nice fit in the T slots, but ran out of shed time, so I'll finish it off tomorrow.
Have fun
Stew