Thanks!
At first I wanted to screw the runners into the van, but that seemed impossible at hte time. I'll try
to explain why. Problem was that I couldn't separate the upper part of the runner from the lower because they are notched just to avoid that. The only way to screw the upper part onto the seat is when the seats are not installed yet so you can slide both halfs far enough to reach the holes in which the bolt go. When placed in the bus, there is not enough space to do that. Get it?
Therefor the only option was to leave the runners on the seats, place the seat into the bus and weld the runners (the seats well protected by heat resistant blanked of course!). But before I could do that, I had to remove the original runners and brackets.
Afterwards, I realised that there might have been a better way (which, I don't know yet :lol
because it isn't done very professionally...
But it's too late now... However, I'm thinking of restoring the bus in a year or so. Maybe two years...
I'll try not to forget to make some picture this weekend and post them.