Front and rear diff/transfer drain and fill

[MisterB]

What front diff do I have?

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[MisterB]

Can you tell from this Pic which transfer case I have?

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[MisterB]

Here is an axle reference. Front is probably a Dana 44, and rear corporate 14 bolt. I believe Dana asked will usually have the model embossed on the center carrier section webbing (44,60,70).

https://ck5.com/forums/resources/axle-identification-chart.10/


Transfer case, find one that looks like your and click on it, then click on specifications for the model number. Probably a new process 205.

https://www.drivetrain.com/parts-ca...acements-and-parts/chevrolet-gm-transfer-case

Thanks for the info. Does this look like the one I have?

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[MisterB]

Here is an axle reference. Front is probably a Dana 44, and rear corporate 14 bolt. I believe Dana asked will usually have the model embossed on the center carrier section webbing (44,60,70).

https://ck5.com/forums/resources/axle-identification-chart.10/


Transfer case, find one that looks like your and click on it, then click on specifications for the model number. Probably a new process 205.

https://www.drivetrain.com/parts-ca...acements-and-parts/chevrolet-gm-transfer-case

As for the transfer case, I have no idea when I compare my Pic to the link you shared. Any ideas?

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[Craig 85]

Looks like a 14 bolt FF rear, 10 bolt GM front axle and a NP-205 transfer case. The rear brakes look to be the 13" x 2.5" drums.

 

[MisterB]

Looks like a 14 bolt FF rear, 10 bolt GM front axle and a NP-205 transfer case. The rear brakes look to be the 13" x 2.5" drums.

What weight gear oil should I run in the front? Any idea general capacity?

How about the NP-205, as far as gear oil/fluid?

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[MisterB]

If you have an 8 lug wheel and there are 10 bolts on the differential cover, you have a Dana. If you have a 6 or 8 lug wheel and there are 14 bolts on the differential cover, it’s a 14 Bolt. If you have 8 lugs on the wheel and 12 bolts on the differential cover, you have a Sterling 10.25.

As far as oil, I use 75W-140. Go on YouTube and you'll find a video of a rear under power with a plastic diff cover installed so you can watch what happens to the oil. You won't believe it! It's very violent and tends to 'wrap' around the ring gear, thus starving the bearings.

The 75W-140 really helps to curb that and your rear end will last allot longer.

Is that 75w-140 the right one for the front diff as well?

What about the transfer case?

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[ali_c20]

Early manuals say 80-90 gear oil. There are later manuals that say atf. I use 80-90 gear oil in my 205 behind a th350. Running without any issues since 6 years.

 

[MisterB]

Early manuals say 80-90 gear oil. There are later manuals that say atf. I use 80-90 gear oil in my 205 behind a th350. Running without any issues since 6 years.

Do I need to change any gaskets when draining and filling the transfer case? I know I need a new gasket for the front diff and one for the rear, but not sure about the transfer case

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[ali_c20]

Not the t-case, except it leaks It has the drain plug at the bottom and the filler hole above.
http://repairguide.autozone.com/zne...00c152/80/07/03/9a/large/0900c1528007039a.gif

 

[MisterB]

Early manuals say 80-90 gear oil. There are later manuals that say atf. I use 80-90 gear oil in my 205 behind a th350. Running without any issues since 6 years.

Looks like the service manual for an 80 4x4 says to use motor oil. I figured the service manual would be much more specific about what transfer case and differentials I have, but it isn't. I'll post screen grabs below

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[MisterB]

Sounds like front and rear differentials call for the same fluid type, although I'll likely upgrade to the thicker fluid recommended here. Sounds like I'll need about 10 quarts total for both?

Transfer case calls for motor oil. Any idea how much?

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[ali_c20]

The np203 (chain driven) needs engine oil. The chain needs thinner oil to lubricate the links and there is a pump in the tailshaft that lubrictaes the rear bearing. The 205 is gear driven. I don't think you could hurt the 205 when using engine oil or atf. I got my 205 from offroad design and they told me to use gear oil. Works since 6 years. It takes ~ 2.5 quarts iirc.

 

[Rick Dobbins]

Yes Eric I would. And we have the same rear end set up!

 

[MisterB]

Got the rear diff drained and filled. I went with full synthetic gear oil in 75w140. Cleaned and degreaser the cover and bolts, and then painted the cover and bolt heads with some Rustoleum black spray on bed liner.

I also drained and filled the transfer case. I used motor oil, since that's what the factory calls for, and I already had some. Ended up using Valvoline 5w30 Max Life synthetic blend. Full synthetic 75w-140 Lucas gear oil already costs a small fortune, so it was nice to be able to use some oil I already had.

Next up is the front diff. I'll do that another day. Need to buy more 75w-140 gear oil.

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