Broadly speaking there have been three main variants of compensator; 1)Original. No hole in underside of bell housing. 2)Uprated - same basic principle as original but with some detail differences in design and materials and has a grease nipple on the actual rotating housing. To access this grease nipple a 50mm(ish) hole is drilled in the underside of the bell housing. 3)Centa - different design principle and as fitted to the 2014 cars. No idea if the bell housing is drilled or not, but probably not.
Separately there seems to have been some variation in the steering racks fitted some of which have a hole in their housing and some do not.
Hope this helps - though I suspect there have been minor variations on these themes right from the get go.
