Spacings for hooks.

Hi all,
I have a 90 Truck Cab, it used to be a hard top and so it doesn't have any of those tie down hooks down the side. I would like to add some but am unsure of the spacings. I'd hate to get it wrong and look like more of a tit than I already am, so I was wandering if anyone would mind having a quick measure and letting me know.
Thanks Tigger

how soon do you want the measurments? can do it tomoz morn

There's no rush. I'm gonna buy a Tonneau cover soon so I'm getting prepared. Thanks very much.

from the back corner to the middle of the first one is 21cm, from the middle of that one to the next one is 40cm and the middle of tht one to the middle of the next one is also 40cm. hope tht makes sence

That makes perfect sense. Thanks very much for doing that I'll buy the hooks soon and get them fitted. Tigger