As I recall, 8.625" lol Stuff from the 8.5" swaps over without a problem.

But NONE of us are fans of the G80... it really is a piece of crap. Unlocks around 25mph... doesn't really like to lock around corners. The locking counterweight likes to break taking the entire rear with it.

Used Auburns are a better buy but can't be rebuilt in the truck. I have an Eaton in my F150 and it's a killer LSD. You could pick up an older 30T clutch style LSD from other vehicles...I think Impala SS and the similar cars had real ones but light preload springs (150-200lbs).