I also believe that they are PSTs not Worthingtons. I have found them very common around these parts... The DOT-E9791 exemption code shown in you pics is for PSTs: http://www.hydro-test.com/files/RESindustrydocs/PST-E9791-Bulletin.pdf Also, I believe production of the 3500psi /7/8" neck tanks stopped long before 2014, switching to the E7 3442psi cylinders with "standard" 3/4" neckshttp://www.hydro-test.com/files/RESindustrydocs/PST-E9791-Bulletin.pdfAre there any special issues with a twinset of HP120 2014 Worthington Steel Cylinders? I think I have deciphered the neck markings correctly.
Nice tanks. (I have 10, 6-100s and 4-120s). The 7/8 neck is a bit of a hassle to find manifolds for, but I've managed to accumulate a few. Keep in mind the the 7/8" neck is smaller than a 3/4" since different classes of thread specifications are used.
If you need parts for the Genesis slant-back valves, reach out to John at Northeast Scuba Supply.