Getting references after a company closes after 17 years as a welding apprentice

The company closed and I am not sure how to reach former colleagues. I am in Louisville, in case local advice matters. A colleague offered to vouch for me. Is a client acceptable?

Thanks for writing this out. I went through something close to it 12 months ago, and it got easier once I kept a simple log of every call and form.

I kept a note of my results so my references could be specific. They appreciated it.