Projects GM 12 bolt help

so i have an 82 gm 12 bolt rear end and i dont know what gears are in it and whether its 1/2 ton or 3/4 ton ive been told its a half by some and 3/4 by others and have been told it has anywhere fron 3.83 to 4.11 ratios so if anyone knows let me know thanks

 

How many lugs? 1/2 ton 2WD was 5x5", 1/2T 4x4 went to six lugs, 3/4 ton they go to eight lugs - at least my '85 3/4T Suburban is an 8-lugger. Plus the 1/2 ton was usually a 10-bolt as far as I know.

Gear wise you can get an idea by turning the yoke and figure how many times you have to turn it to get the hubs to make a complete rotation. 3/4 tons can range from 3.41 to 4.56 with 3.83 and 4.11 the most common, I believe. That I know of there's no tag or ID on them but you can google some rearend sites for more details if you don't want to take the cover off and count teeth.

 

At least some 80's 4x4 1/2 ton rear axles were 12 bolts,they have 6 lugs.The 3/4 ton 8 lug full floater is a larger 14 bolt axle.12 bolt truck 4x4 axle usually has 3.42 gears but factory gears were available from 2.70 something up to 4.11 and maybe beyond.

 

Some 1/2 tons had 12 bolts, kinda rare though.

 

no not rare, they just stopped useing them in the early 80's... the 2x4 axel was 5 lug 1/2 inch stud, the 4x4 was 6 lug 7/16 inch stud, the axels are interchangable, you can swap a 5 and 6 lug axels. Stock gear ratio in 2x4 axel is 3:07 but it can be 3:36 3:42 or 3:73. After market you can go all the way to 5:13

 

Where are the pictures? oh, Mike is new at this...hey Mike, see if you can get some pictures of the rearend, that would help.

Anyways, if it's an 82 12 bolt truck rear then it's a 1/2 ton. Also it could be an earlier rearend swapped into the truck. 3/4 tons were 14 bolt.

 

if you decide to do a gear swap, make certain you order TRUCK gears. Same goes for gaskets, etc. GM 12-bolt CAR is different from GM 12-bolt TRUCK. Take a look in your Summit catalog and you will see what I mean. Believe it or not, the pinion shaft in a TRUCK diff. is smaller than that of a CAR.

 

thanks for the help guys its 6 lug so i guess its halfton and for the gears i will try turning the pinion and if its less than 4.11 im upgrading to 4.88s again thanks and i will try to get you some pics of the new project

 

you turn the drum two revolutions while counting the number of pinion revolutions to get the ratio