From my reading of Atkins, the change from grease to oil axleboxes for iron minks took place during the construction of Lots 172 and 193, in December 1897. I've assumed that date applies to 4-plank wagons too, so 65815 from Lot 161 is a bit touch-and-go for oil boxes. There is a photo of 67389 of Lot 191 with grease boxes. Both the 4-plankers I've built that have kept their Coopercraft oil axleboxes, 71460 of Lot 220 and 10670 of Lot 355, also have cast numberplates, though 71460 might be a little early for that, as the earliest one with cast plates of which I've seen a photo is 73189 of Lot 287 - with oil axleboxes. I'm afraid I've become a bit of a number and Lot junkie.