Scott, some of those Saginaw power steering boxes have a tall tooth on the center of the worm gear. It makes for a very quick response just off the center point, and the ratio slows down as you approach the end of the helix. I think the variable-rate design originally came out on Cadillacs, and pretty soon it was adopted all across the GM carlines. Not too sure about when they started putting them on trucks. It made for very quick lane changes while still allowing a good mechanical advantage for parking maneuvers.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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