[RB26NL]

ATESSA ET-S Pro was was an option for all R33 GT-R's (also non vspec).

How can you check if the pro is installed instead of the standard ATESSA ET-S?

 

[R32 Combat]

Having looked though all the diagrams I have, I'd suggest Pro means A-LSD variant.

V-Specs have Pro, non V-Specs have non pro.

I hope this helps.

 

[Sub Boy]

Have a look at the rear diff.
The ETS-Pro equipped cars have round drive flanges on the diff, where as the non ETS-Pro diffs have cutouts between the bolts on the flanges so it sort of looks like a starfish.
......this is on the diff side flanges, not the drive shafts.

 

[Little Nismo]

The A.LSD warning light on the tach is a dead give away. If you can't find it ypu don't have pro. If you. Need to ask where to look you don't have it. It's that obvious.