Lionel SD70ACe
Scale Wheels
Scale wheels for this locomotive are available directly from Lionel. To order them, you must call (586) 949-4100, select option 2 ("S & O"), and select the "Parts & Warranty" (formerly known as customer service) option. The product number is "LNL6409879625". Their sales department will not recognize that part number, because they are only available via their Parts & Warranty department.
The scale wheelset passes the NASG S-4 wheel standards. Using the NASG gauge, back-to-back is spot-on and flange depth is also spot-on. Wheel width was measured at 0.126".
Scale Fidelity
The pilots move along with the couplers on curves, but are independent of the trucks' swivel. For true scale operations, some modelers have permanently fixed the pilots for a more realistic look, if their layout has large-radius curves.
It has been reported that these engines will run on a DCC-powered layout without modification and tested on multiple DCC platforms. You do not need a Lionel Legacy system. Overall length, and cab width and height, are spot-on or very, very close to prototype measurements. Kadee 802 couplers can be easily installed, with perhaps a 0.010" styrene pad needed. The Micro-Mark Digital Pull Meter showed pulling power at 6.5oz (0.185kg). The engine has a fan-driven smoke unit.
Kadee S-scale couplers are not included, but a bracket for mounting them is.