That is difficult to tell from the picture. Guess you will need to contact them. I searched for your plate and can't believe how the GG gun parts have dried up but I have a parts kit so have not looked in a long time.
I did find the plate you need on Gun Broker but have no idea if this is a fair price to pay for one.
https://www.gunbroker.com/item/1109782740
Interesting that most of my "machine gun" collection needed work, after purchasing. I am very particular and want all my weapons to function. Figure I am a caretaker for my son and the next future owners. JA even reblued some MP44 mags for me that I got cheap but had a lot of exterior rust.
Scott, am I the one that recommended John Andrewski to you regarding your MP40? Can't remember if I did or not, but he sure is a good dude and does excellent work.
You don't see these come up often. I do not own this weapon and don't know the seller.
https://www.sturmgewehr.com/forums/index.php?/topic/40356-wts-amnesty-registered-reising-m55/
Wish this baby could talk! Just a hunch on my part, but would not be surprised it was in Vietnam. The overall condition, patina and pitting, indicates to me it has seen some action. I forgot to include the bayonet I have for it. I just oiled it up, hence the shine on the stock.
I am the current care taker of this M55 which I bought from a fellow board member. I snagged the case about a year ago. The case was almost as hard to find as the M55! I believe a few board members on this forum have owned this particular M55. I have not shot it and may not since it is in such pristine condition. Original slings are hard to come by too!