useable diff or not?

[RAYLEE29]

HI, it looks like a viscous lsd to me, the giveaways being the plate between the crownwheel and the crownwheel carrier,
and its a 3.62 according to the writing on the crownwheel which is also an lsd ratio and normally go for good money.
as for the rust you dont want any pitting on the gears as they will wear quickly what the guy says about holding oil is total b****cks!
if it cleans up ok all well and good if not it wont last long.
out of interest is this for a track car as general concencus is you dont need one for the road.
Ray