As far as trucks go, what Tim said is true but Hydra-matics were quite common in cars. Not just in GM cars either. They were also used in Lincolns, Packards and others.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.