GMC first offered Hydramatics in '53. Chevy followed suit in '54. And although they are not common, they aren't "rare".

"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.