At ADC, the design philosophy carried forward from Peter Pritchard was low effective mass, high compliance, low VTF. The basics of the design were exactly the same ranging across the whole product line from the $5 cartridge in a blister pack sold through Radio Shack up through the Astrion at $400 (in '82, inflation adj for today $1062). The injection molded plastic bodies and stylus holders were of different colors, the output pins identical. The magnetic circuits internally were physically the same parts but the windings of the coils were of different wire sizes and # of turns. So the bodies were substantially the same. If memory serves, there really were only two body configurations. The coil assembly used on the low end of the product line up to and including the QLM36, and the bodies used on all the high line product starting with the XLM. There may have been a slight change around the XLM II Improved, but it wasn't a big deal. Thus, if the stylus holder fits on the can of the body, ADC styli are interchangeable across bodies close to universally. Why bring this up? I've seen lots of questions on here where people have an ADC stylus and want to know if it will fit on another model's body. The biggest question is actually based on the mu-metal can of the body. If you look toward the bottom rear of the can on both sides, there is or is not an L-shaped bump on the can body. That bump was added to the ADC basic body design in 1979 by John Kuehn after some extensive testing and validation. The later bodies with the L bump and the styli that fit them, fit much tighter and much more stably. So now the matrix of compatibility is based on bump/no bump and high line/ low line. And now for the real reasons. The high line was really differentiated by cantilever and diamond selection. Within the bump/high end quadrant lies the most modern and interesting of the ADC product line. XLMII, XLMII Imp, XLMIII, ZLM, Astrion. And within that crowd you find tapered aluminum tube cantilevers on all but the Astrion which was the first sapphire rod cantilever ever used (after extensive testing of Boron rod, Beryllium rod, and the sapphire rod in engr tests and double blind listening tests). Diamond selection at the time included ellipticals, modified ellipticals, the Shibata cut, and some experimentals where the diamond vendors were trying a few things out, particularly different ratios between the bearing and scanning radii. Which cantilever materials and which diamonds do you like and why? I'd love to hear your opinions on these subjects.