Mystery Hook

Bryan
The drawing you have posted is of internal sections. Do you have side and end elevations of the plough as they might give some clues? If it was an original fitment, it would be on those. If it isn't, it narrows it down to a depot 'improvement'.

 

Dug out the other GA plan and scanned the relevant section.
Drop light shown as Droplight. No hooks.
But there again no lamp brackets shown either.

 

Its still not any clearer , the hooks can not be to secure the drop light, and as there are Hooks on both sides, and unless the drop light was hinged and opened side ways then why have hooks on both sides? , i still think is to secure some kind of cover,

 

Maybe that sturdy strap (in the b&w photo) was used to stow something against the vehicle end and the hooks were for tying whatever it was in place with a rope or chain? What the something might be is anyone's guess, of course. It would help if we knew if there was a corresponding strap or similar for whatever it was to rest on further down.