keep the 3 spd or upgrade to a 4 spd

[mjo8585]

hey everyone i have my '68 C-10 2wd and keep getting told to get rid of my 3spd for gas mileage and so the r's aren't so high on the highway. im not sure what to do. I plan on putting in a floor shifter and keeping it a manual. any thoughts? thx for any help!!

[PanelDeland]

If you're looking for milage don't bother with the 4 speed.The final (high gear ratio) in both is 1:1.You'll have more even RPM thru acceleration but the same RPM at cruise.If you want floor shift and improved milage search the FAQ's and build threads for a 5-6 speed swap.

[Hommer]

I just switched my truck from a 3-speed to a 4-speed. It's much better to drive with the extra gear, more fun too! The final drive in a 3- speed is 1:1 ands should be the same in a 4-speed unless you got some kind of overdrive. So it'll pull the same rpms going down the hwy. My 3-speed pulled 2400 doing 60 and so does the 4-speed. You'll only gain an extra gear before the final drive,(1:1). But you'll be happier with the 4-speed,IMO.
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[cam.man67]

Wouldn't bother with it. Like PanelDeland said, the top gear in both cases is 1:1. As for being more fun, again, I don't think a 4-speed is that much more enjoyable to warrant getting rid of your 3-speed.

[raycow]

The only 4 speed that will help your revs and gas mileage is the A833 or MY6 used in GM trucks about 82-87. This is a Mopar car 4 speed with the gears rearranged to give you overdrive in 4th. I recommend this box if you can find one, but they are rather scarce.

Next best would be a T-5 5 speed transmission from an S-10. I put one of these in my truck and love it, but it's not strong enough to withstand dumping the clutch with sticky tires.

Another possibility is a 3 speed + overdrive, which was a factory option until 69, although not many buyers ordered it. You can use one from a passenger car, so they aren't particularly hard to find.

All of the above are affordable and fairly easy to install. The 3 speed + OD is basically a bolt-in.

Ray

[ChevLoRay]

If rowing through the gears is your ticket....just spend the big bucks, do the conversion to a 5-speed and add a GearVendors over/under-drive. That will double your gears and keep you busy.....

[Jacfourteen]

The thing about the 4 speed is that unless you get some non-stock one is that 1st gear is useless. 99% of the time I never use it, it is only helpful if you are crawling in slow traffic (less clutch work), or if you are really loaded and need to go up a steep hill (I didn't need to use first when I had almost 2 tons of gravel in the back or when pulling a 6000 lb trailer. So what I'm saying is my truck might as well be a 3 speed. I would say if you're going to the trouble do a swap to a NV4500 5 sp. or a T-56 6 sp., I am eventually gonna swap but haven't made up my mind as to which one. Good luck and let us know what you decide.