Two Speed Differential
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Two Speed Differential
I've got a 2000 F250 Superduty Crew with V10, automatic and 3.73 LS. Recently moved from a small slide in camper to a 27' 5th wheel. When climbing steeper grades, the gear selection is less than satisfactory. I've been reading up on the US Gear and GearVendors underdrives, but wanted to also investigate changing to a two speed differential. Any experience or advice on what's available?
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just from what ive read on here go with the gearvendors hing similar but the 2 speed rears are next to imosable to find one that will fit and if you do its probable older and your gonna lose the braking power of the newer trucks but thats just my opinion
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Go GearVendors.
This topic has come up several times. One item of particular interest was the alleged 2 speed in late '60s Cougar Eliminators. It was supposed to be a 2 speed 9 inch. (which would do you no good) But as it turned out, it was a Dana with a "Hone Overdrive" used in motorhomes of the day, and there were two (2) prototypes made, never to be seen again.
Truck two speeds are from F600 size trucks going back as far as I know to at least '48, as the old man had a '48 F6, a '51 IH 2 ton, and a '58 F600, all with two speeds. And those rear axles were wayyyyyy too big to fit under a F250 or even these days up to a 550.
I don't think you will see two speed diffs ever for this size, as they are more complicated than the add-on OD, and they add unneeded unsprung weight, which would make the ride and handling of an empty truck unacceptable to most folks.
This topic has come up several times. One item of particular interest was the alleged 2 speed in late '60s Cougar Eliminators. It was supposed to be a 2 speed 9 inch. (which would do you no good) But as it turned out, it was a Dana with a "Hone Overdrive" used in motorhomes of the day, and there were two (2) prototypes made, never to be seen again.
Truck two speeds are from F600 size trucks going back as far as I know to at least '48, as the old man had a '48 F6, a '51 IH 2 ton, and a '58 F600, all with two speeds. And those rear axles were wayyyyyy too big to fit under a F250 or even these days up to a 550.
I don't think you will see two speed diffs ever for this size, as they are more complicated than the add-on OD, and they add unneeded unsprung weight, which would make the ride and handling of an empty truck unacceptable to most folks.
Last edited by 85e150; May 20, 2006 at 12:23 AM.
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Thanks for the insights. I took time to ask about recommended differential shops in the area. Came across a shop owner who took the time to answer questions about what was available including the underdrive units. Turns out that the existing 3.73 LS can be changed to a 4.10 and use the existing LS. Cost would be just under $1000. Figure that would give me most of what I'm looking for, as a majority of drive time is unloaded, but need the better gearing for the occasional over the pass time. Probably go that way.
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Joined: Aug 2004
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From: Lynnwood, WA
Occasionally, they do pop up on eBay, but since they're old, finding parts for them could be difficult, to say the least. If I were you I'd go for a gearvendor underdrive if the F250 is mixed use, or a gear change if its mostly a tow vehicle.
