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Old 02-28-2011, 10:11 PM   #26
special-K
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Re: Rear gears

Because it's cool to have a factory dash tach in a truck. Who really needs a tach anyway? The highest performance vehicle I have is my Harley and that has no tach. I listen to the motor. Most trucks have automatics that shift themselves.I've always put tachs in what I drive because it says performance,like cool wheels and tires or dual exhaust. Extra gauges in cars from the '60s and early '70s set them off. Same with trucks.
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Old 03-05-2011, 10:15 PM   #27
chvtrkman
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Re: Rear gears

I've got the same HO52 diff in my '69 C-20..I always thought the ratio was a 4:56, but I suppose if it's actually a 4:57 I wasn't far off..Anyway, my engine spun @ 3000 rpm when doing 55 mph, but since yanking the 3 spd saginaw out and replacing with a 4 spd OD, the rpm is down to 2200 @ 55 mph...Don't know if this helps you at all, but I much prefer being able to hear myself talk when trying to have a conversation with a passenger.
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Old 03-05-2011, 11:31 PM   #28
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Re: Rear gears

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Originally Posted by chvtrkman View Post
replacing with a 4 spd OD, the rpm is down to 2200 @ 55 mph..
Always nice when not having to change out the rear end. Any specifics on the year and model of this 4 spd OD, and modifications necessary?
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Old 03-06-2011, 08:57 AM   #29
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Re: Rear gears

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Originally Posted by Longhorn Man View Post
they sucked when they were new, add 40 years to them and they are craptastic at best.
I still don't get it why people go ga-ga over them.
Its the cool factor of having that center hole filled with something.
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Old 03-15-2011, 04:53 PM   #30
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Re: Rear gears

Factorystock,Sorry I lost track of this thread...my kids were on the computer and I forgot to go back to it. The tranny I swapped for the 3 spd is a New Process GM MY6...They were used in Chevy trucks from early to mid 80s I believe.My goal was to improve my gas mileage a bit w/o having to change rear end gears.while it did get the revs down some, I still only get 10-11 mpg.

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69 C-20 292, 4 spd O/D, 4:56 rears. No a/c p/s p/b p/w......restoration project,"Operation:Stovebolt"
78 C-10 305 TH350 new (old) daily driver
02 Suburban Z71 a.k.a. the family truckster
99 Silverado 1500 Z71
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