Yes, SPSF's pointed you at a nice pin-vise. Mark the coupler pocket fixing screw positions with something pointed and a small hammer, then drill with a #50, put a 2-56 tap bit in it, then the 2-56 screws going in smoothly will bring a smile to your face.
Hardest part is getting those two marks in the right place. Treat yourself to a 2-56 tap set with tapered and parallel taps, start with the tapered. More treats - drill set containing that #50.
Are the Lionel floors diecast or steel? Being self-taught, I usually play it safe and back the tap out occasionally on thick stuff, especially diecast, to clear the cut metal (swarf!) out. Have fun - do it on scrap first?
Jason
