decode front and rear diffs?

[Kain]

trying to figure out what they are,and i know you never know whats in them till you pop them open

the rear had a bunch of numbers 3896839 gm75 a281

the front i could only find 38396

is there something im missing?

 

[diesel4me]

Rear axles on the 70's to 87's had a 3 letter code stamped on the axle tube somewhere-(like "CDL as an example)"-the book says the code is on the right side tube on the upper surface near a shock mount,but I've found them on the left tube and on the bottom,wherever the person felt like stamping it that day I guess..

I've had to wire brush both axle tubes before finally finding the code,then was lucky if I could read them,and then had to call a dealer or use a Hollander interchange manual and have them look up the ratio going by the code,they could also tell if it was a posi too..

Its faster and easier to pull the diff cover and read the numbers stamped on the ring gear,and use your calculator to divide the larger number into the smaller one..(example--if it says "41-11" it has 4.11 ratio gears)..the diffs probably need a good lube change anyway...

 

[AR_K5]

Its faster and easier to pull the diff cover and read the numbers stamped on the ring gear,and use your calculator to divide the larger number into the smaller one..(example--if it says "41-11" it has 4.11 ratio gears)..the diffs probably need a good lube change anyway...

Uh… 41-11 is 3.73 gears.
41-10 is 4.10 gears

 

[diesel4me]

Yeah,I was just going by memory and giving an example......at any rate its faster to just take off the diff cover and look for the numbers or count teeth and divide the results to get the ratio determined,than to waste time cleaning off the axle tubes looking for the code--someone might have swapped gears in it already,rendering the factory codes worthless...it also lets you see if any teeth are boggered or missing,and what shape the spider gears and pin and the bearings are in too...

 

[Kain]

i was just wondering weather there 12 bolt 14 bolt or ???

 

[AR_K5]

How many bolts around the diff cover?

 

[72blazerguy]

i was just wondering weather there 12 bolt 14 bolt or ???

You can tell by looking at them. This might help...

1/2&3/4 ton Front axle possibilities: Dana 44, Corp 10 bolt (8 lug in 3/4 ton)
1/2 ton Rear axle : Corp 12 bolt, Corp 10 bolt
3/4 ton rear: Corp 14 bolt full floater, 14 bolt semi floater (9.5 ring gear)

1 ton: Dana 60 front, 14 bolt rear

Dually and earlier than 1972 have some other combos.

Post up a picture if you can't figure it out off of this chart.

 

[Kain]

12 bolts

 

[Kain]

by the chart its 12 bolt truck

 

[Kain]

thanks for the chart

 

[wasted wages]

Now that you have the chart,, If you ever come across any of those old junk Dana 60 front axles,,, those things are worthless...

Just call me and I'll drive up to Lubbock to take them off of your hands... save you the trouble of hauling them to the scrap yard..

 

[AR_K5]

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