I have a 1983 F-150 4x4, no bolt rear. It is either an 8.8 or 9" rear. Tag has:
FL B 2M09
L08 8 8S8 22A
Which rear gear do I have and how might I tell?

 

That's a mystery.

An 83 should have a 9". But that tag is definitely from an 8.8" axle.

The tag reads 3.08 limited slip, 8.8" ring gear.

Is there a large cover on the back of the differential held on by bolts all the way around? maybe 12 or so of them? If so, it's an 8.8" axle. If there's no removable cover on the back, it's a 9".

 

Hey, thanks for the info. It does have a bolt on cover on the rear, Must be 8.8". I bought the truck used so maybe it was changed later.