As much as it is a shame, an 86 Trooper is probably worth $0 and whatever it will bring at the current price of scrap. Worse, it might actually be worth negative dollars as you might have to pay someone to haul it off. So, in the end, of course they are going to total it. The cost of having a body shop just touch it is going to exceed its value.

I know such reality is painful, but it is a 22 year old vehicle that never held its value to start with. If you want to fight their totaling of it, the best you can do is scour (and it will require serious scouring) the want ads and other used car listings for other vehicles like it and present those to your company as comparable values for yours. It won't be easy.

Good Luck,
Michael