L3200HST No fuel shut off valve?

[drcdac]

Does anyone know the fuel line size so I can put a shut off valve inline?
Kubota put the filter in a bad position and I keep scraping it with tree branches while clearing a lot. Then not only do I loose the filter bowel but 10 gallons of diesel.
Thanks

 

[Bulldog]

It's been so long since I put my cutoff on mine I'm not sure. Please don't hold me to it but for some reason I think it was 1/4 but I may be wrong.