Relevant points from the article:
---The tests were run at Big Moose, NY, on the New York Central's Adirondack Division: location chosen because the grade was a good simulation of the ruling grade on the Boston and Albany. (Actual grade not mentioned.)
---First test, 9 August 1967. Involved (EMD GP40) 3055, (GE U30B) 2845, and (Alco C430) 430-3. At this time the C430 was about six months old: it was one of the first units built with Alco's "Hi-Ad" truck, the earlier C430 (built for the Reading) having had conventional trucks. (The U30B was even newer: New York Central's second lot of U30B, units 2840-2857, were built in July-September of 1967.) Water leaked into the forward sandbox of the U30B,so usable results were obtained only from the other units.
---(I think this is from a report on the first test): "It is felt that the average speed of the 3055 was higher than that of the 430-3 account the ability of the 3055 to maintain higher average traction motor current because of better wheel slip control" and "No improvement in adhesion which could be credited to the high-adhesion designed truck on Unit 430-3 was noted." (Quoted from NYC test report.)
---McMillan goes on:"In fact, observers on the ground commented that this truck appeared to be quite unstable and 'jumpy' when wheel slip did occur."
---Alco was obviously disappointed. "As a result, Alco made design modifications to the wheel-slip detection and correction system on unit 430-3. After testing at the Alco plant, the builder requested that NYC re-test the unit."
---Further tests were run (using both 430-3 and 430-1) on 28-29 September, 1967, and of the units from the three builders on 8-10 November.
---Best tonnage performances, all on wet rail, and the average speed of the hauls were
------GP40: 1,568 tons at 12.32 mph
------U30B: 1,801 tons at 10.6 mph
------C430: 1,740 tons at 16.25 mph
(Comment: the low speed of the GE unit struck me. Perhaps it was due to automatic power reduction at low speeds if, as Typewriters speculates, the GE unit had Automatic Power Matching.)
Interestingly, New York Central had already, in July 1967, ordered the ten C430 it purchased BEFORE the first test.
(Stephen McMillan's article was in "Diesel Era," vol. 15, no. 5. Rather than look for my copy, I am working from the bit "excerpted" from the article on p. 133 of the book "Alco's Century Series: Volume 1 - Four-axle Models," Withers Publishing, 2003.)