Help with Rear Wheel Seals

I am looking to replace the rear wheel seals on my 56 S120 3/4 ton full floating axle. I went to NAPA Auto today and they show 5 different choices. Looking at the Rockauto site I see about the same thing. Can anyone steer me in the right direction with this? This will be special order including freight through NAPA so I'd like to get it right the first time. I'm not a fan of Rockauto mainly because of their lack of customer service so they'd be my last choice for this. Any help will be greatly appreciated!

I just went through this a couple months ago with my S120 4x4 panel. From the LST I knew it was an RA10 rear axle so that helped me choose the OSN 27SS3272. To be sure, at napaonline if you open up each individual seal choice it will give you dimensions which you can check against what you have.

I just went through this a couple months ago with my S120 4x4 panel. From the LST I knew it was an RA10 rear axle so that helped me choose the OSN 27SS3272. To be sure, at napaonline if you open up each individual seal choice it will give you dimensions which you can check against what you have.

Thanks. My line setting ticket is long gone. Would I be able to identify the axle by any numbers or stampings on it? I took my measurements in inches and fractions I'll have to get on it with my calipers and check it in thousands tomorrow but it looks like one of the group will fit as it translates pretty close and the description mentions RA 10 non dualie.

Not sure if this will help or not.

I looked for my line setting ticket for my S120 to find the axle it has, no luck. However I found the notes from the prior owner. He was a machinist. I knew him for a long time, great man. He took good notes, so from his notes the Axel Seal - rear is 455008, Federal Mogul #'s.

If you put the number in as a search at Rock Auto it comes up as a part for International.

Best way is to pull one out and either get the number off the old seal or measure and match it with one of the mfg "seal finder app's". No guessing and no worries that some had been changed since the truck was built.
Most seals can be "overnighted" if you really need it right away.
IHC ( and the same is true for other mfg) used off the shelf seals from seal mfg. All you need is bore, shaft and depth measurements to bring up all seals that fit. then it is a matter of selecting the best type for the application, Either the buyer guide or the supplier should be able to help.
Unitized seals are best if available, followed by 2 piece seals ( Stemco type), last place are 1 piece "grease seals that ride directly on the shaft.
Ask anyone who has done a lot of seals and they will have their favorite, and you'll get as many different answers as there are mfg , I favor CR Classic seals as I have had the best luck with them.

Remember these bearings ride outside the rear axle and need to be hand packed with grease,

there are lots of debate on this, probably starting one by writing this,

but starting with dry bearings hoping they will be lubed by axle gear lube can be disastrous,

Thanks everyone, this has been a wealth of information.

Bedrock John, Good point to mention packing the bearings, I always have on axles that get their lubrication from the differential. I figure even if you live on a really twisty road the bearings are going to run dry at least for a few miles which can't be good for them.