Ihave a millermatic 200 with the original ka-18 gun. I need to replace with a good replacement but not some astronautical price. I do not weld enough for that kind of costs. Which one would y'all recommend. Something middle of the road.
Make sure you can get consumables. Tips and liners.
That said, most guns where Ive worked were replaced first day the new welder came with Bernards or Tregaskis (same company today) depending on the shop.
You may want to consider original whip length and get the same. A longer whip can be nice but the drive system may not be up for pushing the extra length. Definitely want to be able to get consumables . If you are friendly with your local welding supply, you may ask if they have any take offs.
Part of the reason I suggested the gun above is that it uses Tweco consumables that are every where.
If I were to guess it is a Tweco Weldskill copy from the look of it.
I run a 15' 300 amp Bernard Centerfire on my Millermatic 252 because I like the Centerfire style. I also have a 25' Tweco(not sure if it's a Classic or a Weldskill), it works but I would not use it long term as it is tough on the drive motor.