What size bolt is this

These are a specialty bolt that you won't find at any hardware store, and rarely at an auto parts store. Typical practice is to find the pair on a similar vehicle in the salvage yard. A lot of them now have at least a section where you take your own tools and you can spend all day there. Also consider doing a search for "Pull-A-Part' to see if they have a yard near you. I've been to 16 of them, and all were very clean and well-organized. Employees and customers were always very friendly and helpful, and parts aren't very expensive. You can do an inventory search too to see which yards have vehicles like yours, but they can't tell you which parts have already been removed or are damaged, and they can't tell you colors and optional equipment.

There's a lot of similar pick-your-own-parts yards popping up around the country, but none are as clean as the Pull-A-Part yards.

The alternative is to buy new bolts from the dealer. They'll have a listing of the size, but they go by application when they order them. Either way you'll be sure they have the proper hardness.

So nobody knows what size they are or what other vehicles have the same bolts? Because pull-a-part doesn't have any Isuzu Troopers.

There's two things you can try. The first is to visit the dealer's parts department and have them look up that part. They should be able to find the size and thread pitch. Don't expect them to have memorized what other applications use the same bolt unless one of their people used to be a mechanic and is familiar with brake systems on all the other models. Replacement bolts aren't a commonly-asked-for part, so they won't know the specifics about it without looking it up.

The second choice is to take an old bolt to an auto parts store and see if they can look up a "Heli-Coil" repair kit. That's not the type of information they provide on their web sites. You'll have to go right to the store. Heli-Coil inserts are designed to repair stripped-out threads in the part the bolt is going into. The kit includes the correct size drill bit to drill out the damaged threads, and it includes the proper tap to make new, larger-diameter threads in that hole. The last step is to thread in one of the stainless steel inserts with a special tool. That insert leaves you with new threads of the original diameter and pitch as the original ones were. All you need is to find the listing in one of their books that tells which kit is required for your bolt, then, the bolt size will be listed on that kit and probably in the book too.

If the bolt threads are not damaged, they also have gauges to measure the bolt. Hardware stores will have those gauges too, but they might not have replacements of the same hardness.

You might also look for a Dodge Raider. That was an unpopular model that wasn't around very long, and I remember it was an import model with Dodge emblems plastered on it. It looked just like the Trooper.

I got a better picture of it.

That's not going to be a hardware store item. You're going to have to visit the dealer or a salvage yard.

Dang i can't find an Isuzu Trooper warehouse.

What part of the country are you in?

There's a 1999 and a 1995 model in El Paso, TX in the Pull-A-Part yard. I thought they had added a yard in New Mexico, but I don't see it on the list.