H1b Out of cap - is old i797 mandatory

I got my H1B lottery picked in 2016 and case was approved and later i didn’t use it or never went for stamping.
Also the employer didn’t provide me the I797 doc.

If i want to do out of cap now, do we need to get the copy of that old I797 or with the case number we can proceed .
Any help is much appreciated .