locking differential - which one is it?

[TheAustrian]

I found the genuine optional equipment list of my '79 Blazer. It has many optional equipment listet, among is a locking differential with code 1G80. I was told that GM offered two types of locking differential's. A limited slip differential and a 100% automatic locking differential (the M1009 CUCV where equipped with this 100% automatic locking diff.). Can anybody tell by the Code which locking type I have with my 12 Bolt rear diff?

 

[NEK5]

not positive, but maybe you look up the rpo code for your year truck

 

[pauly383]

I would bet its the Eaton locking tyoe , commonly known as Gov Loc . I thought the limited slip was mostly for the earlier trucks . It wouldn't hurt to find out , as you should change the differential fluid anyway when you procure a used truck

 

[TheAustrian]

not positive, but maybe you look up the rpo code for your year truck

that was fast

"rpo code" - what's that?

 

[NEK5]

that was fast

"rpo code" - what's that?

there all the little codes found in you glove box, all on like a 4x6 sticker...come to think of it, i`m not even sure if your year has them....i`m sure someone will chime in....

 

[pauly383]

G80 is the rpo for a locking differential , but earlier 12 bolt rears were limited slip type and later ones were Eaton locking types . We have done this post before 3 times a year

 

[resurrected_jimmy]

http://www.fl-thirdgen.org/rpo/rpo.html this will help you figure out what most of the codes mean

 

[pauly383]

The code is going to be G80 whether its one type or the other .

 

[OrangeCrushK10]

I'm voting for Gov-loc based on year and such, but it's worth a check.

 

[TheAustrian]

there all the little codes found in you glove box, all on like a 4x6 sticker...come to think of it, i`m not even sure if your year has them....i`m sure someone will chime in....

yes, this list is the 4x6 sticker from the glove box.

 

[TheAustrian]

Okay, since my K5 is a 79 I think it cannot be called as early 12 Bolt - correct? And if I open the gear cover, what will I see to identify which type is installed? I mean what will tell me it is a limited slip or a Eaton locker? Sorry if my question sounds dumb...

And...does it make a difference when I change the pinion and ring? I think not...?

 

[pauly383]

Okay, since my K5 is a 79 I think it cannot be called as early 12 Bolt - correct? And if I open the gear cover, what will I see to identify which type is installed? I mean what will tell me it is a limited slip or a Eaton locker? Sorry if my question sounds dumb...

And...does it make a difference when I change the pinion and ring? I think not...?

The earlier type has big springs in the center , visible on both open spots of the carrier .

The later one that actually locks solid at low speeds only , has a big giant block visible in the center spot of the carrier going to both sides between the gears , and the center pin goes through the center , and another part that you could move with your finger , and it would spring back .

Ring and pinions don't care what differential carrier . The only requirement is the carrier has the right size for the gears , some are for higher ratios , and some lower ratios . The gears themselves don't really care for much as long as they get some oil and an easy break in

 

[TheAustrian]

@Paul383

thank you for your explaination! I think I will be able to identify now.