Gordon,
As a youngster(1973) I stumbled on to the grade along HWY 160 by accident. I soon obtained Robert Ormes' "Tracking Ghost Railroads In Colorado" and absorbed the history.
An easy way to pick up the grade is to take the turnoff to Dyke/Cat Creek Road (marked by Hwy sign) from 160 approx. 10(?) miles west of Pagosa. You can drive right up next to the old mercantile store at Dyke where the grade is obvious. You'll even find a couple of sticks of rail, tie remnants and various chunks of track material. It is private property off of the road and I always tread lightly. From here you can trace the grade back toward Gato/Pagosa Jct. Also, if you head back down 160 to the east, the grade will be just to the south of the road for a few miles. Years back I parked at the Swiss Chalet style real estate office east of Dyke and walked back west along the grade. East from this point the grade deviates from the Hwy and is spotty.
Check it out when you have a chance.