251SI Gas fitting change

[kaizen]

I'm getting tired of changing these fittings. I have many welders and NEVER have broke another but on my 3rd from Everlast. I'd like to just put a long nipple and another standard gas fitting I can get in any welding supply. Yes I realize it will be just hanging there but I can deal with that. I just can't deal with cheap parts that throw the whole project timeline off.
I believe i measured the inner small pipe as 3/8-24 fine thread and the gas connection as 5/8. Most 5/8 i see have 1/4 inch mpt on the inside and I think i need a reducing nipple but not seeing npt to fine thread. Can anyone confirm or point me in the right direction?

[performance]

They break from over tightening. Very rare problem unless you put excessive force on it. Are you holding one side when you tighten the other as well? (using 2 wrenches)