Vulcan Arms Underfolder receivers.

Does anyone have experience with these for an underfolder polish build.  Do they have the renforcement plates? Any feedback or opinions welcomed.

Also, I know that in the past these Vulcan receivers had the serial numbers on the rear of the receivers and the underfolder parts would cover up the SN.  Does anyone know if this problem has been fixed by Vulcan?

Iam in the process of building my first AK, It is a polish underfold and I have a vulcan reciever,  This reciever came off a disassembled rifle. I have taken only 3 hours to fit the trunions to the reciever, only four holes had to be worked so I used .5 oversized Monel rivets to put her together, the reciever was heat treated in all the right areas, there is no reinforcing plated on it, After assenbly I twist checked it like an aircraft spar and found that it is very very tight and rigid, My opinion is that it is a good reciever, No extra work was needed to fit the bolt carrier. I would like to try an unfinished reciever next on my romi kit and see how that goes. I will put some pics on when I get a chance. BTW triple check the length of the rivets to be used, this will make the job so much nicer, the serial number is on the front right side and the manufacture info is on the rear left.