Hello everyone. Merry Christmas and Happy New Year.

I recently purchased this Ludwig 6-ply 14 X 13 power tom shell that I'm going to have cut down and build a 14 X 8 Snare out of. I received the shell exactly as you see it the pictures. No hardware, wrap or badge. My question is does anyone know what era it's from. I have a feeling it's large keystone Monroe Badge era shell but is it from the late 80's or early 90's?? In pictures 3 and 4 there's a stamp or tattoo as I call it on the shell. Looks like Q.A.and a checkmark. I'm assuming it's an inspection stamp. Has anyone seen this stamp before and know possibly when it's from. I want to put the correct badge on it once I've converted it into a snare.

Any help would be appreciated.