According to Utah Rails-- On October 29, 1984, the parent company of the D&RGW railroad, Rio Grande Industries, was purchased by the Anschutz Corporation. Several pieces of equipment were refurbished and repainted. The 20 newest locomotives on the railroad, the 17 SD50s (new in September 1984) and the three GP60s (new in May 1990), were delivered in this newest shade. When seen together with the other two shades of orange (the original Aspen Gold and intermediate Kansas City Orange), the later shade is obviously different.
So, based on this, unless the SD40T-2's were repainted (which I'm not aware they ever were) they should ALL have the lighter orange logos-- NOT the Wheeling Orange-