Today I had a look at the detail behind mounting the oil cooler, and ended up making a few of the spacers needed for bolting to the engine baffles. In doing so I noticed that I'm missing a length of AT6-058-5/16 tube. I went to my packing list for the Firewall Forward Kit and sure enough, I didn't tick this part off when doing my inventory ..... 18 months ago. Too late now to ask Vans to send me another short length.
I did have a short length of the same size tube left over from another part of the build, which was enough to make a couple of the spacers. I'll order some more tube from Vans later.