Rear main seal replacement

[bigbadchev84]

I searched and didnt find a whole lot of info. I have a 350 in my 72' blazer. It started out as a front trasfer case output seal and now i have the whole truck tore apart right now and the drivetrain ripped out.

What seal do I get? single lip, double lip, double offset lip? the one that was in there was a single, but it was leaking, so is there an upgraded one out there?

Also any tips on installing it?

 

[4X4HIGH]

I'm assuming you have the two piece rear main seal engine so I would go with the double lip seal (pretty much the standard these days). They do make a teflon version which seals much better than the others.

 

[Blue85]

Is this available in the two-piece? I see a Felpro for $30:

Part Number: 2912
Alternate Part Number: RS30140
PerformanceFor high performance engines only. Premium fluoroelastomer. 2 piece high vacuum.

And then a National for $18:

NATIONAL Part # 5274 Oil Seal Kit; PTFE, Shaft Size=3.74", Outer Diameter=4.54", Width=0.492" Rear; PTFE Rubber

But I can't find any website with a picture of it or stating whether it is one-piece or two.

Then the Fel-pro for $8 says "improved design." What is improved about it?

FEL-PRO Part # BS118291 {#BS11829} Rear Main Seal Set
Type: Rear Main Seal Set; Rubber; Two-piece; Offset double lip; Improved design; Rear