My 66 was never going to stay clean, I like my Diesels a least a little bit dirty ! The other thing I have disliked is the big N gauge style coupler on the front end, given the layout is non shunting scenic running, it was never going to be needed.
After removing the coupler I extended the buffer beam down with an offcut of black plasti card and added a couple of bits of wire for pipework using a proto picture as a guide.
Weathering is diluted railmatch "sleeper grime" applied with a brush. It still needs a link for the coupling.
Eagle eyed observers will also notice a pair of container flats have been added to the small N gauge fleet (pre weathered video to follow)