Unusual CDA buffers

[The Fatadder]

But if a random one, while looking at photos for weathering inspiration I came across a photo of a CDA that had been fitted with rectangular buffers.

 

A little more research and I’ve now found a second (375075 and 375118). The latter there is a photo on the wagons on the web Flickr page showing in 2001

 

im trying to verify when these modifications were first done, to see if any wagons would have been fitted with these buffers as early as 1999 (possibly as part of the refurb activity that was taking place at that time)

 

clear numbered photos of CDA in that period are sadly lacking 

 

https://ukrailwaypics.smugmug.com/UKRailRollingstock/C-tops-codes/CDA-china-clay-hoppers/i-35dKP2S/A

 

does anyone have any info?