3/4 ton vs 1/2 ton

[Cochinito]

I own a 77 3/4 ton C20 8 lug and I have a 85 1/2 ton 5 lug C10. I was told that swapping the whole suspension and the differential from the C10 to the C20 I would have better fuel economy. The only thing we won't swap is the chassis.

Also, I would like to know what are the pros and cons on having a c20 3/4 ton truck vs a c10 1/2 ton truck?

I know I would be better off fixing the 1/2 ton but here is the problem is that the 77 used to belong to my grandfather who passed away few years ago and has sentimental value to my family. So, we want to restore it and keep it in the family.

[enaberif]

Difference in fuel economy will be negligible at best.

Your driving a 5,000lb square truck if you want fuel economy buy a civic.

[Cochinito]

Hahaha he said civic

[Irish_Alley]

there is a slight thickness difference on the frame. you cant just swap a axle from 1 ton to a ½ ton and think you can haul 1 ton stuff. you have to think about the springs and frame also. i know thats not what your asking but the only difference you might see in swapping axles is a different gear ratio. the ½ should have a high gear than the ¾ or 1 ton (i.e. 3.08 in the ½ vs 4.10) and that will give you better rpms at highway speeds but slower take off speed.

if you want better mpg a more efficient motor or a overdrive trans will help. but the money you put into that might not equal the small amount of mpgs your might save. your best/cheapest bet is your right foot, drive it like gramps would and stay under 60. my 79 k20 with 6" lift and 38s with a 350 sm465 would get 7-8 driving it like a teenage boy if i drove it like gramps and under 60 it would go up to 10. my 91 v3500 crew cab with a 350 tbi and a 4l80e trans and 28" tires would get 12ish (never had a gps on it so i dont know the correct mileage) i swapped the 350 out with a 5.9 and its getting 16 (gps) with 33" tires. both trucks have 4.10 ratios but the crew cab weights just under 8000 lbs 

[Cochinito]

Is there a kit to change the axel ratio from 4.10 to 3.08?

[Irish_Alley]

Not really a kit but you can buy new a ring and pinion but that's going to be a few hundred bucks then a couple special tools and its not a drop it in and go you have to get it just right and have to use shims. It's cheaper and easier if you search craigs list or find them in the junkyard. Pop the cover off and find out what ratio it is find the numbers on the ring (circled in blue) and divide the 41 by 10 and you have 4.10


Nice write up where I found that picture at also. (If the pictures not working then just click the link it will tell you on there)
http://www.pirate4x4.com/tech/billavista/Gear_Setup/

But you might not be able to find gears that low in a 8 lug setup. And your 8 lug axle might not be able to accept gears too high.
But you can look up your stuff on here

http://www.ringpinion.com/

[roundhouse]

You could just install taller tires
Same result as changing axle gears


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