Mystery bolts in 1989 Ford E-150?

[buzltbeer]

Hoping someone might have knowledge of what these mystery bolts are holding in the floor of my van, it's a 1989 Ford E-150 that was somewhat built out with insulation and boards.  There are 4 bolts in the back that I can't tell what they might be holding, I can't see from underneath and I'm just worried if I grind them off I might be sorry.  You can see them in this video  at 3:13, they might just be holding the board down that is on the floor.

 

[MrNoodly]

Since they're on top of the aftermarket carpeting, my guess is that they probably used to anchor a bench seat that folded down to become a bed. That was common in conversion vans.

 

[highdesertranger]

I am assuming you are talking about the ones that you can see that run side to side? Instead of cutting them why don't you just unbolt them?

Highdesertranger

 

[PlethoraOfGuns]

Those look like aftermarket grade 5 bolts from the hardware store. Ford would use weird flanged bolts for stuff. Who knows what those could be for. Try unscrewing one.

 

[buzltbeer]

Thanks all, I was worried about just unbolting it and hearing my rear gas tank hit the ground.

 

[Sofisintown]

You can see them in this video  at 3:13, they might just be holding the board down that is on the floor.

I would crawl under and see what they are holding up.
It is not hard to distinguish them, you can measure or look for newer bolts and nuts.