Great info!
The info I have is my serial number welder had a 2 wire motor...
Miller confirmed this on the phone and said "115VDC, 1/20th hp, 3560rpm, with 40:1 reduction gearbox".... so 90rpm ish
Larry Burros said he had a 2 wire and a 5 wire motor, but when I emailed him for a price, I didn't hear back...
So I called him... and he was super helpful, and obviously knew his stuff, but he said he would let me know....

Which seemed to mean sometime in the future... LOL
So, if my motor originally ran on 115VDC, can I use a 90VDC motor?
If not, then is the a PCB I can put in my welder that outputs 24dc so I can find a more modern wire feed system???