10 and 12 bolt axle number locations.....

[Brokeblazer79]

Trying to figure out where this number is so I can verify what gears my truck has. Any help would be greatly appreciated. Also wondering where I would find the casting numbers...........

 

[lectric80]

The only way that I am certain to find out the gear ratio is to pull the diff covers and look at the stamped numbers on the ring gear.

Alternately, you can jack the truck up and rotate the tires and count driveline revolutions. That would be the easiest way without pulling the covers.

 

[chulisohombre]

i havent had one in yrs,but i remember io think the number being on the top side of the pumkin above the filler hole on the 12 bolt.10 bolt couldnt help ya,never had one.i dont know if the casting number will tell you what gears it has though.you may have to pull the diff cover on one of them and look at the ring gear.it will be stamped on there what ratio it has.or lift the rear mark the driveshaft and spin the tire one time and count the number of time the d shaft goes around to get a pretty close estimate

 

[pauly383]

Considering their age , and since you don't know the gears ....... drain the oil , pull cover , and check the side of the ring gear ..... the oil needs changing anyway

 

[Brokeblazer79]

Got the axle numbers off it anyone able to decode them ??????
RCM 064W91 and 3896839 and this had an N below it and I also found a GM79 Casting number............. These numbers are off the 12 bolt.......

 

[chulisohombre]

Got the axle numbers off it anyone able to decode them ??????
RCM 064W91 and 3896839 and this had an N below it and I also found a GM79 Casting number............. These numbers are off the 12 bolt.......

you definitely need to pull the diff cover and find the numbers on the ring gear.it is much easier.41.11 is for 3.73 gears.you divde the big number by the small.this is what was stamped on my ring gear on the old 12 bolt i had.i know nothing about the casting number on the case itself.maybe someone else can decifer that for ya.but i think the only true way to look is to look at the ring gear stamp.

 

[pauly383]

Everyone who comes into an old truck should pull the cover anyway and change the oil , most people NEVER change the rigs gear oil .