here is my earlier post on those caps

Hi,

On my GQ's trunnion swivel, the hole in which the trunnion or king pin bearing cups reside, also contains a sheet metal disc with a seal called a king pin cap. These are available from Mr Nissan (only?) and are a bit over $30 each. I suppose an enterprising type might be able to do something with a sheet metal disc and silicone, but the originals are not flat.

If I had thought more about why the opening had two little half moons on either side, I would not know how much they cost

While the manual says to remove them with a brass drift, after my first attempt, I found a suitable punch that looked remarkably like a straight blade screw driver shank did the job, because it could be fitted down neatly into that half moon slot, carefully alongside the edge seal on the king pin plug. I make no guarantees that you'll get all of yours out ok, but having learned my lesson on #1, I got the other three out ok.