Hi Pete,
It's exactly 2mm high but I've a drawing bailey-morris supplied for the same part way back when I was first getting quotes and that says 3mm max. You can see the diff input flange below. There is a very shallow recess to fit into and in this instance, I can see that I need to spend some time cleaning the surface up a bit too as there's a small amount of rust left in there. I really could do with getting the face of the diff flange machined too as you can see some corrosion top and bottom where it wasn't covered by the original BMW UJ.
