I don't believe that there was a stainless speaker grill or ashtray, that was available for the AD truck. The glove box was available in stainless, up until 1951. There were an upper and lower stainless grill bars. They framed the top and the bottom of the radio speaker grill. They were a separate pieces from the actual radio grill. The upper bar had "Chevrolet" embossed in the bar. Or "GMC", depending on the make. The ashtray had a stainless pull available for it, up until 1951. I suppose that you could have gone to your local Chevrolet dealership and purchased these stainless components, if you purchased a 52 or 53. And replaced the painted ones, that came were standard on them. Perhaps somebody makes a reproduction "stainless" speaker grill and ashtray cover. Or, you could have a good steel set chromed. I have not had the actual experience of taking apart a number or stock AD trucks, like a lot of our fellow Stovebolters. I certainly do not pretend to know everything. Somebody told me once, But, I feel like a did a fair job in researching this issue for my restoration. Hope this helps. Good luck with your restoration.
Rugo