Transfer case fluid

[Creedsmyname]

Hey,

I'm looking to see what fluid I put in my 76' K10 transfer case. The fluid that is in there is too lightweight, so every time I drive it I have a small puddle under the truck because it is seeping around seals.

Any answers would be appreciated.

[DustyRusty]

Hey, Creed.  Welcome to the site.

We need to know what transfer case you have.  It's probably a full-time NP203 or a part-time NP205.  Does your truck have lock-out hubs?  Or, can you get us a picture of the back side of the t-case?

IIRC, the NP203 uses 30 wt. engine oil and the NP205 uses regular gear oil, GL-5 or equivalent.

This thread will help identify what you have:  http://forum.73-87chevytrucks.com/smforum/index.php?topic=28740.msg239915#msg239915

[bake74]

     Also welcome to the site. 
     In the 76 service manual which can be found in the tech section, on page 7M-3 (page 203) 3 or 4 speed manual transmission should have the 205, the automatic transmission should have the 203.
     Unfortunately this manual does not have the lubrication for transfer cases, it say's to see the "truck chassis service manual" (#8 procedure on right side of page), which we do not have.
    Well I have the 76 truck chassis service manual downloaded on my computer, unfortunately it says the exact same thing and in the lubrication charts it shows nothing for the transfer cases.
     As DustyRusty stated, the 203 uses 30 weight motor oil, 80w gear oil is what is called for in the 205.
     

[Creedsmyname]

Sorry about the lack of info on that, but it is the NP205, so I just put in the 80W-90  GL-5 gear oil. The guy who owned it before put in a light weight ATF fluid, so I have a puddle under the truck every time I drive it anywhere. Hoping that this fixes my problem. Thanks for the info.