1988 Gmc Sierra Sle Locking Differential

token2004 · October 16, 2011

I just bought this truck.. I realized the other day that the driveshaft has a tiny bit of play in the rear end when I grab it and turn it back and forth (about 1/2 inch) so I'm assuming the ring and pinion are wearing out? There is no play what-so-ever in the u-joints. Anyways, for since the truck will see allot of mud anyways I want a locking rear diff.. but I was wondering what one is best? And if my truck is 10, 12 or 14 bolt?

My dad's k1500 Chevy has one in it.. but I don't know which one.. except that its ratcheting.. but a friend of mine said for most of them you need a switch on your dash when his does not?

Thanks!

00Silverado4x4 · October 16, 2011

Do a search for lockers and you will find lots of options. The factory option for these trucks is the G80. It's completely automatic, no switch. They all have pros & cons so it's a matter of what you like & what you want it to do for you. My G80 has been great for all purposes & I use my truck for everything on & off road. As far as your rear end just count the bolts on the differential cover and that will tell what bolt count you have. Standard duty is usually 10 from my experience (including current truck).

token2004 · October 20, 2011

I checked in my glove box and I can't find G80 any where??

Also lets say I want 8 inches of lift on my truck.. whats the best route?

00Silverado4x4 · October 20, 2011

I'm not one to ask about lifts but there a lot of threads about lifts too. Should all be in the suspension section.

token2004 · October 20, 2011

Where exactly should G80 be located?

Also is it normal to be able to 'wiggle' your drive shaft back and forth about 1/2 an inch in the rear? Its not the u-joints.. actually goes into the diff

Stevens03 · October 20, 2011

Where exactly should G80 be located?
Also is it normal to be able to 'wiggle' your drive shaft back and forth about 1/2 an inch in the rear? Its not the u-joints.. actually goes into the diff

I think on the 88's it would be on the door jam. It would have many different codes with it as well. And yes, it's normal to be able to turn the drive shaft back and forth some. GM's drive line isn't exactly known to be "tight" Not necessarily a bad thing either.

token2004 · October 20, 2011

Okay.. I forgot to mention that if I crack the throttle and let right off fast it clunks back there as well? I dont wanna to blow my rear end way out in the bush... wasn't pretty when my dad blew his right through the cover in his '91.. but he has 33's on it. thanks

00Silverado4x4 · October 20, 2011

Okay.. I forgot to mention that if I crack the throttle and let right off fast it clunks back there as well? I dont wanna to blow my rear end way out in the bush... wasn't pretty when my dad blew his right through the cover in his '91.. but he has 33's on it. thanks

Mine has always done that in my '06. If it's not normal than something has been wrong in my truck for the 5+ years I've owned it. Although mine sounds more like a clunk in the trans vs the rear end.