i do apologise for invading someones territory, new at this game. wickerman
It seems you have somehow got muddled in with Drew, how we have no idea, I have reported some of your posts and hopefully they will be able to separate you.
Do you also post as Joe Taylor and Blazer_oner because you seemed to be answering for them in the threads I pointed out above.????
Sincerest apologies, forgot to answer this morning, not knowing which van you have, access is the only difficulty, unless they butchered the seat base, on a Ducato van you just need to remove the seat from the base, you'll need a T40 Torx key/socket there are two horizontal at the front of the seat, push the seat right back to see them easily, then push the seat all the way forward to access the ones in the seats sliding rail, when you get to the last one be careful, as these seat are incredibly heavy.
The actual seat has been removed here, but it makes pointing to the bolts you need to take out better, I prefer to take put the whole thing sliders and all, refitting is so much easier and the weight difference is negligible.