1 of 2 Lower Control Arm pivot shaft fixing bolt broken

I'm currently replacing most of the front end suspension components on my '90 MM 2wd.
While removing the 2 fixing nuts for the rearward plate of the LCA (Driver's side), one of the bolts that appear to be pressed into the frame rail sheared off.
Is this flat-backed bolt indeed pressed in or is it tacked on there? It's tough to tell.

Where can I get one of these bolts besides going to the dealership?

I'm guessing at this point that I will need to grind the back off of the bolt. I noticed that the bushing presses against this so I guess I can't just use any old nut/bolt.

Pic is attached. Any advice appreciated.

Thanks,

Jay

I left out a few words in my last post, hopefully the picture was clear enough, but since no one's answered I thought I'd try and clarify....since I was typing on my Surface 2, there was some weirdness with IE and this site and not all that I typed made it into the post.

So...I was removing the 2 nuts that hold on the rearward-facing plate for the LCA pivot shaft. The front-facing nut for the LCA pivot shaft it that big nut (18mm I think).

I'm sure someone on here as broken one of those. I'm just looking for the least tedious way to fix this.

Thanks again.

That will have to be either drilled out or ground off from the back side. Take a regular bolt of the same size, grind down the head, and weld it on in the same place as the original