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General Site Info => General Discussion => Topic started by: 83gmc on August 28, 2004, 07:09:00 pm

Title: unlock the secret
Post by: 83gmc on August 28, 2004, 07:09:00 pm

Hi all, i recently got an 83 heavy 3/4 ton GMC,
how can i tell if the rear end has a locking differential or not?
Thanks alot!!

Title: Re: unlock the secret
Post by: roundedline on August 30, 2004, 10:11:00 pm

have you checked in the glovebox for the spec sheet?

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

Title: Re: unlock the secret
Post by: TRUCK6DRIVER on August 31, 2004, 06:08:00 pm

With the trans in park, jack up both rear wheels and rotate one tire. If it will not turn it is a limited slip or posi. If the other tire rotates in the opposit direction it is an open rear.
Ray

Title: Re: unlock the secret
Post by: bigblock73 on September 14, 2004, 12:24:00 pm

Ray, normally that would be a good way to check...BUT, if the posi is worn out then it will act like an open carrier when this test is performed.

I say pull the cover, check for the posi, then replace the gasket and fluid...you get the real answer and maintenance all in one.    

...Jeff

'73 swb 2wd
'77 Blazer 2wd

73-87.com

Title: Re: unlock the secret
Post by: Fast68 on October 13, 2004, 04:56:00 pm

plus gov loc wont lock until 100 rpm or more difference happens from one axle shaft to the other

remove the axle cover, its the only real way to know, no matter hwat the SPID label says, its an old truck now who knows whats been swapped/done/installed by now


good luck