Nantucket Sleighride is a pretty good album without a doubt and the song Travellin' In The Dark always sticks in my mind along with the title track but I personally prefer the first album Mountain Climbing. I read a few months ago that Leslie West didn't like the song Nantucket Sleighride much in the early days although it grew on him overtime.
Mountain happens to be one of my top 10 all time favourite early/mid 1970s heavy rock bands and I have got around 20 Mountain cds from the 1970s & 1980s along with a number of West Bruce & Laing cds as well.