[brad1]

Does anyone know what gears came stock in a 1977 c10??
Right now the truck has on it an oblong 12 bolt 8.875.
Does anyone know what gears came originally in this truck?

[brad1]

I am sorry, it is a 1967....

[jimfulco]

I think it depends on what engine came in it, I-6 or V-8. The way I heard it, V-8s came with 3.08, and I-6s got 3.73, but I can't say for sure if that's true. Sometimes there's an option list inside the glovebox door.

If you don't get a definite answer here, try over at www.67-72chevytrucks.com/vboard

[Crosley]

I am not sure what 'stock' is in all the trucks of these years ..

as jim mentions :

I had 2 six cylinder trucks = 1968 and a 1969 both had 3.73 gears 2 wheel drive

My 71 chev truck V-8 long bed truck had 3.08 gears. 2 wheel drive truck

I'd suggest the 'spin the rear tires and watch the drive shaft rotation" for gear ratio

[brad1]

hmmmmmm. I lifted the rear of the truck in the air, marked the tire and the driveshaft, spun the tire...............

The drive shaft made barely over 2 turns for every 1 turn of the tire..

surely I dont have a 2. something in the rear end....

I guess I need to unbolt the cap and take a look.

What all is involved in this proccess?

[Crosley]

Originally Posted by brad1

hmmmmmm. I lifted the rear of the truck in the air, marked the tire and the driveshaft, spun the tire...............

The drive shaft made barely over 2 turns for every 1 turn of the tire..

surely I dont have a 2. something in the rear end....

I guess I need to unbolt the cap and take a look.

What all is involved in this proccess?

you spun both tires at the same rate and counted 2 turns on the drive shaft?

[matt167]

tag should be in the glovebox... my dad has a '72 C/10 Custom, might have changed from the first year to the last year of that generation, but it is a 350/ Auto, heavy duty springs and 3.73 axle, 2wd.. so I think they could be ordered with anything... my grandfather had a '67 GMC K25. 305E V6, SM420 4spd, 4x4 and 4.56 axles

[jimfulco]

Jack up ONE rear wheel and turn it over TWICE while you count driveshaft revs. If you jack up both wheels with an open differential, the wheel you can't see can turn, and that will throw your result off.

[M&M CUSTOM]

You would be better off unbolting the cover (make sure to have a pan underneath it to catch the up to 2 and a half quarts of fluid AFTER buying a new gasket and 3 quarts of gear oil- odds are it hasn't been changed in a long time anyway) changing the fluid is never a bad thing and you also get to see the gear pattern to check for wear as well as SEE what gear ratio is in there. You will see a set of numbers on the ring gear like 41:10 which would be a 4.10 ratio gear set.

Clean as much of the old oil out, I just use a can of starting fluid and a bunch of rags, but that's just me- everything gets saved in barrels for an oil burning heating stove for the winter.

[fast68]

howdy there,

yes, the teeth count of both gears are stamped into both gears, just divide them to get the ratio of the set. also the date code is stamped into them as well.

the best way is to get the stamping off the pass side axle tube between the diff housing and the shock mount it is three letter and you need to wirebrush the axle tube to find the stamping

then call the chevy dealer parts counter and tell thenm 67 c-10 pickup and the code they will look it up

or jack oen wheel off the ground and mark the driveshaft and use the wheel valve stem to count ten revolutions while you have someone count how many times the driveshaft mark goes by

divide the driveshaft mark times by 10

it will be 3.07, 3.73 or 4.10 in which is the only three ratios these trucks got

3.07 and 3.73 are the most common

check glovebox sticker and see if its on there, it will be a G- code such as GU6 etc


i can look up the axle stamping code if the dealer wont for you, as i have a book for these old truck 12 bolt axle codes.

nice 67 there how did you first mistake it for a 77 haha

ive owned billions of old chevy trucks, i grew up on the 67-72 era and i miss them all




good luck!

[prostreet6t9]

X 2 on pulling the rear cover. Unless you know the history of the truck you never know if someone has done a ratio change or lost a rearend and Installed a Boneyard unit at one time,The stickers or tags won't do much good.

And if you don't know the history it would be a good Idea to change the oil and make sure everything looks good. It's better to catch the small problems before they become BIG problems.

[Drewnashty]

My '76 C10 with 350 V8 and Th-350 came with 3.08 in the 12 bolt 8.875" rear end. As stated earlier the only way to be for sure is to take the diff cover off and count yo teefus.