Seat belts

[Martinez]

I’m fitting new seats into my 2001 hi bingo. Anyone know if the newer seat belts can also be fitted to the van ?

[Martinez]

Having taken the seats out to replace them, does anyone know which spacer fits where under the seats ?
I know there’s a steel spacer under where the seatbelt mount point is and on other side at the rear there was just a thick plastic spacer, but where do the front ones go ? Both have rubber surrounds but are different thicknesses.
I also seem to have a spare plastic spacer about 3mm thick. Any ideas ?