Orange sticker on the rear pumpkin will indicate a limited slip rear. Also, the axle code that Nismo mentioned will tell you limited slip and gear ratio.
Here is mine. You'll notice the location that reads AXLE then under it it says HG49.
HG - Limited Slip
49 - 4.90 gear ratio
Other than that,
The rear axle H233b, has 33 spline axle shafts, 233mm ring gear.
Front axle R200A, had 28 spline hubs and bolt on CV joints, & 200mm ring gear. Not sure what the spline count is at the differential to the CV brackets. Front diff is always open and to my knowledge, not available with a limited slip.