[black79k20]

I am replacing the front and rear output shaft seals on a NP203 in my '79 K20. I have a few questions I would llike to get answered before I tear into this project. I was told the nut holding the yoke on the rear output shaft is a 1 5/16" and to remove the nut I would need a thin wall socket. Is this correct..? I was told the nut on the front output shaft is 1 1/8"..? Will I need a thin wall socket for the front nut as well. Thanks guys..

Matt

 

[Chevman]

Hey, I would like to know as well. Except, I'm doing a front drive seal on an NP205. I'm going to try to do this without removing the whole transfer case--support the drivetrain with a jack, remove the crossmember. Hopefully, it can be done easily. I'm tired of it pissing oil everywhere.

 

[CHEVY]

Use a regular socket for these guys. A impact socket has a tendency to run fat to hold the socket together. Use a Crapsman or a snap-on socket in case you break it you can replace it. I'm not sure on the sizes, but this is what I've done. Your going to probaly need a yoke puller to get the yokes off the splined shaft. I made one out of some 5/8" thick flat stock and a 5/8 grade 8 bolt.

 

[wyldman]

He's right on using a regular chrome socket.It has thinner walls,and will do the trick.

On the front output yoke,you can use a regular socket,as it a flat flange with a nut that isn't realy recessed much.

I've never needed a yoke puller to get them off.

It's easier sometimes to remove the front output shaft bearing retainer and replace the seal with it out.

It also helps to use a small amount of silicone on the yoke spines,so fluid will not seep out under the nut.

Don't forget to drain the fluid first.I'd refill with synthetic afterwards.The NP203 uses 10W30 (Mobil 1 works well),and the NP205 uses 80W90.Any cheap synthetic gear oil will do.

BTW,if you have a part time kit in the 203,don't forget to overfill it by at least 1 inch,and you must use synthetic,or it won't last.Running it in 4WD once a week helps too.

 

[Alan]

Some of the output yokes are a tight fit on just about every 1 5/16" socket. When I was searching for one that fit the only brand that was slim enough to work on what I had then was Snap-On. They had it in 1/2" drive, everything else I found was 3/4" drive and as a result was a bunch thicker.

 

[Chevman]

I finally replaced the seal on my NP205. I did not need to take the cross member out to get the bearing retainer off. It was easier than I thought. I used Wyldman's tip on putting silicone on the output shaft splines. No more leaking!!!

Some notes: To remove the nut securing the front output shaft flange, you'll need a 1-1/8" socket to get the job done--on an NP205 at least. Also, I noticed that the new seal that I got from NAPA looked different from the factory seal. The new seal had two lips instead of the factory's one. I hope that means it's better.

I'm so glad that I don't have to get underneath my truck every few weeks to add oil to my transfer case now