How do I know what size rear pinion flange seal I need?

[JamesLond]

I've come across data that mentions 8.25", 8.625", and 9.5". How do I known which one I have?

 

[Erickk120]

Look at your back diff cover, if you have 10 bolts you have a GM 10 bolt 8.5/8.6 ring gear, if you have 14 bolts you have the 9.5 inch ring gear, the 8.25 inch is the front IFS differential.

 

[JamesLond]

Look at your back diff cover, if you have 10 bolts you have a GM 10 bolt 8.5/8.6 ring gear, if you have 14 bolts you have the 9.5 inch ring gear, the 8.25 inch is the front IFS differential.

Ok, great. Looks like I have 10 so it'll be a 8.625" seal.

Does anyone know if any choice will do? I see OEM w/ PN# 26064028, but then lower priced Timken, AC Delco, & National with oddly the same PN# 710506.

 

[Erickk120]

I would go with the most expensive choice, even if it turns out to be the same you dont want to be doing that thing again, and check for grooves on the surface of the pinion yoke sealing surface. I my self love the yukon mighty seal for these, it just looks superior. Could be just me but its a nice piece. Been running mine for several years with not even a hint of oil.