Found it! (Parts of my collection of old railfan and model railroading magazines are systematically organized. "Motive Power" by and large went into the other part.)
So. The article, "The Design of Locomotive Bogies," by Peter Clark, is in "Motive Power," issue number 4, of February 1999, pp. 4-7. The magazine is still in business (I found their WWWebsite by searching "motive power magazine"), and has a number of back issues still available, but none this far back. I'm not sure of the legalities as to scanning the whole thing and posting it here: moderator please advise me?
Clark discusses several bogie ("truck" in American) designs: the GE FB-3, the Dofasco, the Alco 3-axle "Hi-AD," and cast and fabricated versions of the GE "Roller Blades." All have seen use in Australia, particularly on Alco and GE designed locomotives for the Western Australian iron ore railroads. These are (mostly) heavily engineered heavy haul lines, and since being built in the 1960s have been operated with North American style high horsepower 6-axle locomotives, of types differing only slightly (typical change: more radiator capacity for operation in a very hot desert) from domestic U.S. and Canadian models.
GE's FB-3 was introduced (domestically) in 1966. Clark says "While it did not actually use any EMD patent designs, it was clearly similar in concept to the Flexicoil [except for] us[ing] rubber/metal sandwich construction secondary springs, while EMD were still using coils at that time. The rubber/metal sandwich was very stiff vertically, confining most movement to the primary springs, but was relatively soft laterally, absorbing shocks that would have been transmitted to the locomotive frame."
The Alco truck (used on C636 and some C630) was introduced in 1967. According to Clark, in its initial advertising Alco called it a "High Speed" truck, switching to "Hi-Ad" later. (AH comment: I think the Alco two-axle Hi-Ad, as used on most C430, one order of LIRR C420, and one each of C415 and T6 for the MCRR, was legitimately described as a High Adhesion truck. Perhaps Alco advertising … confused the attributes of the two truck designs?)
Clark says of it: "It had large widely spaced coil springs, and the bolster was connected to the frame with low level traction rods. The coil springs were mounted on rubber pads, giving more lateral freedom. This produced an excellent high speed bogie, that rode very well, and its adhesion performance was on a par with its contemporaries, but in no way was it a 'High Adhesion' bogie."
I'll post further summaries and excerpts later, about the Dofasco and GE designs. For tonight I'll finish with a relevant comparison between units with the Alco and Dofasco trucks. Mt. Newman Mining, one of the Western Australian iron ore railroads, had a fleet of C636 and M636 locomotives (all, I think, built by licensees in Australia). Their railroad is very well engineered, with "relatively gentle" curves, and they specified the Alco truck "even on Montreal designed locomotives." Eventually they were forced to accept the Dofasco truck on their later units "but they never liked it." According to Clark, most of the units with Alco trucks were rebuilt with GE power (AH comment: these units have a unique, Australia-only cab, but otherwise look, to an American, like weird Alco-GE hybrids: C636 trucks and fuel tanks below the frame, but C36-7 or C40-8 long hoods above!), but the newer units with Dofasco trucks were scrapped sold or donated to museums. And: "Six GE locomotives were built new with the floating bolster bogie, but they are not as popular as the Alco bogied rebuilds."
To be continued.