Green’s Dictionary of Slang

(a) have, e.g. coulda, musta, shoulda, woulda.

1928		T.A. Dorgan in Zwilling TAD Lex. (1993) 29: Passing by a bunch of big operators who have just joined the I Shoulda Club.
1937		P. Cheyney Dames Don’t Care (1960) 53: A pompadour that woulda made Marie Antoinette look like a big cheese.
1947		N. Algren Neon Wilderness (1986) 44: You shoulda seen him when the coppers bust it [i.e. a fight] up.
1957		Laurents & Sondheim West Side Story I i: You shoulda done worse.
1963		‘Nino Culotta’ Gone Fishin’ 183: Coulda bowled me over with a feather when I seen ’im haulin’ ’em in.
1975		E. Torres Carlito’s Way 70: If it was up to me they coulda buried you.
1985		J. Wambaugh Secrets of Harry Bright (1986) 115: I shoulda put Boy George between those two gender benders.
1996		(con. 1949) G. Pelecanos Big Blowdown (1999) 248: You had me dead to rights, right up on me. You coulda beat the hell out of me.
2000		J.J. Connolly Layer Cake 176: He woulda been after your little ring-piece if he was still around.

(b) to, e.g. gonna, gotta, oughta, wanna.

1919		Noble Sissle ‘How Ya Gonna Keep ’Em Down on the Farm?’ 🎵 How ’ya gonna keep them away from Broadway, / Jazzin’ around, / And paintin’ the town?
1923		H.C. Witwer Fighting Blood 64: I’m gonna slap you for a Chinese ash can and send you back to that slab in Jersey on a shutter!
1938		G. Greene Brighton Rock (1943) 163: It oughta be on me [...] But I’m cleaned out.
1945		Louis Jordan ‘Reconversion Blues’ 🎵 If someone say ‘for the duration’ Brother, I’m gonna blow my fuse.
1967		P. Thomas Down These Mean Streets (1970) 200: I never figured on getting hooked all the way. I was only gonna play it for a Pepsi-Cola kick.
1972		D. Jenkins Semi-Tough 167: [He] is gonna get himself ass-deep in so much young Scotch that this palatial suite of ours better be able to float.
1990		(con. early 1950s) J. Ellroy L.A. Confidential 66: Some Bureau guys are gonna burn in this thing and you’re gonna have to work with friends of theirs.
2001		Clown Dog Riot homepage 🌐 Clockin grips is cool... you oughta try it Josh, wuss.

(c) of, e.g. cuppa n., lotsa n., lotta n.