A good assessment of this lens. The AIS 105/2.5, 135/3.5 and 135/2.8 all look very similar. They all have have an identical shape from the aperture ring up to the focus ring (apart from the different aperture and focus scales). It is only from the slide-out hood upwards that the lenses appear different - the 105 is shorter, the 135/3.5 has a hood the same diameter as the 105 but is overall longer, the 135/2.8 has a wider diameter to accommodate the faster aperture and is overall a little longer too.
I wouldn't be surprised of the focus ring of the 135 f/3.5 and f/2.8 are the same part since the focal length, focus scale and focus throw are the same on the two lenses. I think with the AI-S line Nikon tried to standardise parts and construction much more than previous versions.
I prefer the AI 135/3.5 over the AIS, the focus throw is longer, the hood is a little deeper and is less wobbly when extended.
