Green’s Dictionary of Slang

1. tough, spirited, brave.

1941		B. Schulberg What Makes Sammy Run? (1992) 252: I had the impression of a chunky, gutty pony, stepping way up in class.
1953		T. Runyon In For Life 106: They were the gutty ones who stood alone [...] instead of whimpering.
1967		F. Salas Tattoo the Wicked Cross (1981) 308: I thought you were gutty.
1974		C. Loken Come Monday Morning 67: Russ had to hand it to her all right she was a gutty little devil.
1983		N. Proffitt Gardens of Stone (1985) 16: Riding in jeeps, full of admiration for the lean ability of that gutty little snub-nosed vehicle.
2005		Robert L. Buenger An Old Kid from Wyoming 191: If the truth were known, I wasn’t necessarily ‘that gutty’, just that impulsive.

2. unpleasant, hard to bear.

1970		‘Metropolitan Police Sl.’ in P. Laurie Scotland Yard (1972) 323: gutty: tedious, difficult to bear.
1981		J. Sullivan ‘Christmas Crackers’ Only Fools and Horses [TV script] Life’s been pretty gutty for Earl quite recently.