Help ID an old 1/2in impact wrench

[Curtis4]

I’ve had this impact in my tool box forever I’ve never used it because I haven’t had a air compressor big enough to run air tools but now I do and was wondering if you guys could tell me what brand it is to maybe find a replacement trigger. I can’t find a part number anywhere the only thing imprinted on it is the Japan by the air chuck.

 

[unslow1]

that reminds me of an IG 231.

 

[bcschief]

IR231 or IR244 or a copy of such

 

[brownbagg]

that an ir 231, best impact ever made. that what all the tire people use