1985 Chevy c60 ramp truck with a 1970 454, early sm465, & 2 speed Rearend????

[Masstowingllc]

I have 1985 Chevy c60 ramp truck with a 1970 454, early sm465, & 2 speed Rearend. So can I change the Rearend gears so when in high I can go like 65 mph and get better mileage also I am trying to figure out how to get better. Mileage and highway speeds out of this big truck? Thank you in advance
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[C10 - C90 Bill]

Finding the higher gears would be the biggest problem. You might try calling a Chevy truck dealer to see if any are available, or if they were ever available.

If nothing works out for you, you could try taller tires, especially if you are running low profile tires now.

Bill

[Masstowingllc]

This has 20 inch rims its a big tow truck this is one step down from a big rig basically I just wanted to know if I could leave low the way it is and change the high gears to something better for gas or like use the high as low and change the high to make it do way better on highway
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[C10 - C90 Bill]

Well, I would still check with your local dealer on the gear question.

The 20 Inch wheels are the norm on your truck, but what size tires are you running?

And are you sure they aren't Low Profiles? Believe it or not, tire size can make a notice-able difference, and a cheaper way to boot.

[Masstowingllc]

No they are ply tires not radials
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[66Submarine]

I'm not an expert on anything, much less the "heavies". But, if you already have the two speed rear I think you probably already have 6.40/8.72 ratios, which were pretty much standard. The low range is a planetary reduction of the high/direct range, not another gear set.

You might could find an axle out of a diesel truck with ratios like you like, given that a diesel rear will be designed for lower engine speeds. Or you could look at finding an overdrive five speed trans out of another big truck. You could also consider swapping out the thirsty BBC for a smaller 350 or something if you don't need all the power. You'll still be screaming along at 3,500+ going 65, but you should use less fuel doing so.

Hope this helps.

[ky-donzi]

Why not go to a 5 speed od trans? Would be cheaper and easier probably
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[alabama mike]

does it have Budd wheels or Dayton wheels? and the reason I ask is if it has budds you can get the centers cut out and put into 22.5 wheels, then you have a large number of sizes to choose from, Might be some up front expense but would be worth it in the long run!

[C10 - C90 Bill]

Originally Posted by ky-donzi

Why not go to a 5 speed od trans? Would be cheaper and easier probably
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I've always known them to be real hard to find. Something that would bolt right in anyway.

Bill

[ky-donzi]

Np540 would be, but how bout a nv4500, it would be strong enough, probably less effort than swapping gears in the rear,,,
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[C10 - C90 Bill]

Originally Posted by ky-donzi

Np540 would be, but how bout a nv4500, it would be strong enough, probably less effort than swapping gears in the rear,,,
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A few years back, I tried to find an Overdrive for my '72 C-10 as well as my '68 C-30. I just love the idea of having a 5-Speed with an OD in my trucks. I didn't check into it very deep, but deep enough to realize that there was no easy way, unless I received the wrong or incomplete info. I mentioned the NP540 to some very knowledge-able guys and didn't get a big green light. I did a quick research just now and found this below. Although I'm a member over there and have talked about the subject over there, this is not my post.

Hopefully it will clear up some info and I welcome anything that anyone can contribute as it is a subject that I am still very interested in. Also notice another poster also saying that the OD Trans is "hard to find".

http://www.stovebolt.com/ubbthreads/...&Number=814855

Bill

[Masstowingllc]

Well i would rather not change tranny since i have put a lot of work into it and tbis in 4th is 1 to 1
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[mrolds88]

I think the trans option would be the best route. Look at a Spicer 3053A (I think thats the right variant). They came mostly in military trucks. It might be the best option.