I've seen repro's of this type of gauge panel, but this one looks to be original... no idea what it originally came in. Chrome plated with a ribbed edge. It had a homemade stainless insert with a speedometer of some sort in it. Picked it up at a local swap meet, thought it was cool... didn't pay too much for it, is it worth anything?
The absolutely most popular Stewart Warner panel that was first made around 1948. Originally intended for the boat market, was called the "Ensign" I believe. Quickly adopted by hotrodders when they saw how easily it fit in their car's (especially '32's) dashboards. Was probably still being stamped into the 1970's, and supposedly a warehouse stash was found a few years ago and being sold by a rod parts retailer. I think their new ads say they are all gone now. The old originals usually go for around $150, more or less depending on the condition of the chrome and if all the light sockets and studs are still on the backside. You say your's is missing the original insert, so maybe worth a little less. Depends on the day.
It was either Parr or Southern Rods who found the stash. That one shown from Parr is a new repro (in aluminum).