The GMC CCKW

I have truck from Norwegian stock, recently I did some measurements of grease nipples and it turned out that there is mixture of metric and imperial threads. Probably at some time Norwegian service guys rebored and rethreaded some places to insert M10x1 grease nipples (spanner size 11). Please if anyone would like to venture under his truck and check what is correct imperial size ???
is it ¼-28 (spanner 5/16) only or are they other sizes ??
also are all fittings (on drivetrain, spring mounts and tie rods) and same ???? or do they differ in size ???
finally do European and US grease gun differ in claw size ??? I seem to have one original fitting but there is no way I could use it for greasing since it is considerably smaller for my grease gun ???

I have recently been through my truck and changed all the grease nipples, I too had a mixture or large, small, straight, 45*, and 90* fittings, with a mixture of spanner sizes. They were however all Imperial thread of 1/4-28.

I think its just a case of different manufacturer.

When I replaced the grease nipples( when I was growing up the local mechanics called them " grease zerks" ) and they were all SAE thread inch, but all different angles. The wrenched used was a 1/4 inch.