The Stovebolt Site Forums The Shop Area Engine Shop rear end questions for my '65 c10 ?

Rear Axle: posi-traction with a .300 gear. (when ya turn one wheel and the other wheel turns on it's own - with both wheels in the air, that's a posit, right?)

I went to the FAQ section of the West Coast Differentials Website and I surfed over there to the Tech Information / FAQs area and read about how to figure this stuff out.

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ok, so what were the options for gear ratios in 1965? I've read about a 3.08 rear gear - which maybe that is what I have since I haven't popped the diff cover off. I've been flippin' around in my '63 and '65 shop manuals and I have not found anything yet about what was offered or available... tho' it is possible I'm looking int he wrong sections....

Now, what about the rear end gear oil? What is the modern stuff you should use? If I roll up to the modern day parts store and need a new rear end diff cover gasket... what do I tell them I need? How often should the gear oil be changed?

Thanks.

-W

I don't know what your truck had in it from the factory, sounds like a lot has been changed. I am assuming the rear gears were swapped. Any idea what the truck had for engine/tranny from the factory? Straight six and 3 speed had either 4.10 or 3.73, iirc. There was also a powerglide behind the 283, but I don't know what they had. The heavy half had 4.10 gears. If something had high gears, it was 3.07.

Sounds like you have a posi, provided both wheels turn the same direction. If so, you need to either buy gear lube additive for the posi or lube with the additive in it.

Best way to get the gasket is to count the bolts on the cover, should be either 10 or 12. I avoid the modern chain parts store, do most of my business at a mom & pop store. Yes, they charge a bit more, but the service is worth it.

All of those around here closed up... it's all incompetent chain stores, which is why I asked. Thanks Fred T.

-W

Give looking up for a 69 C-10 a try. A standard 10 bolt or 12 bolt cover didn't change for years. Another option for parts is MotherTruckers on the 67-72 board. He's in Florida, the other day he posted that he had a lot of differential rebuild parts.

Standard "open" differential" is what you have, most likely... It's the "spider gears" that cause the other wheel to turn, in the opposite direction... Count the bolts on your cover, 10 or 12 bolts if it's 1/2 ton... It will have 6 lug nuts to hold the wheel on. 14 bolts if a 3/4 or 1 ton rear, 8 lug nuts for the wheel... Use a high quality 85/95 weight gear lube and fill to the bottom of the filler hole...
When you open the case, literal "muck" may come out. That's the old fluid mixing with condensation over the years, unless the vehicle traveled through water deeper than the axle, then it may have sucked water through the vent...
Check this too! Replace the vent hose if cracked and make sure it mounts up above the axle and not dragging. You can use RTV in place of an actual gasket. Apply a 1/4 inch bead around the cover and bolt holes, Torque to about 12 ft/lbs, in a criss-cross pattern, let cure overnight and you're good to go... I change my rear diff. fluid yearly, BUT normal use shouldn't require service more than every 2 or 3 years...
While you're in there check for abnormal or excessive wear on the ring gear and spider gears. You'll see 4 small gears mounted inside the ring gear carrier, these are the spider gears. Nice sharp edges and no chips, should mean it's in good condition... Check to see if the carrier is excessively loose by trying to wiggle it with a long, heavy screwdriver... Although excessive wear will make itself known to you by vibration... So FEEL the rear with your butt!
Good luck!