Hi End In Sight,
Sure, I have references aplenty.
Here the 8 individuals in the Ariyan Sangha are graded by strength of their Indriya:
Monks, there are these five faculties. What five? The faculty of faith, the faculty of energy, the faculty of mindfulness, the faculty of concentration, the faculty of wisdom. These are the five faculties. One who has completed and fulfilled these five faculties is an arahant. If they are weaker than that, one is practising for the realisation of the fruit of arahantship; if still weaker, one is a non-returner; if still weaker, one is practising for the realisation of the fruit of non-returning; if still weaker, one is a once-returner; if still weaker, one is practising for the realisation of the fruit of once-returning; if still weaker, one is a stream-enterer; if still weaker, one is practising for the realisation of the fruit of stream-entry.
http://www.facebook.com/note.php?note_id=121689574513398
Here, gifts are being spoken of as being given to those on the way to witnessing Stream-Entry:
‘An offering to one on the way to witnessing the fruit of stream-entry can be expected to repay incalculably; what could I say of an offering to a stream-enterer?’
http://www.greatwesternvehicle.org/swiftpair.pdf
Here is Piya Tan's exposition of the concept, he claims that one enters the path to stream entry on achievement of the fourth purification (2nd Nana), one becomes a Cula Sotapanna a la Visuddhimagga.
The one's on the way to achieving Stream Entry (said to be incapable of dying without attaining it) are referred to as Dhamma-Followers or Faith-Followers here:
http://dharmafarer.org/wordpress/wp-content/uploads/2009/12/16.7-Anicca-Cakkhu-S-s25.1-piya.pdf
If you want to google more you can try these terms:
Truth Follower, Dhammanusari, Dhammanusarin, Faith-Follower, Dhamma-Follower, Conviction-Follower, follower through faith, wisdom follower (idk lawl), saddhanusari
For suttic references try:
The Alagaddupama Sutta:
"In the Dhamma thus well-proclaimed by me — clear, open, evident, stripped of rags — those monks who have abandoned the three fetters, with the attenuation of passion, aversion, & delusion, are all once-returners who, on returning only one more time to this world, will make an ending to stress. This is how the Dhamma well-proclaimed by me is clear, open, evident, stripped of rags.
"In the Dhamma thus well-proclaimed by me — clear, open, evident, stripped of rags — those monks who have abandoned the three fetters, are all stream-winners, steadfast, never again destined for states of woe, headed for self-awakening. This is how the Dhamma well-proclaimed by me is clear, open, evident, stripped of rags.
"In the Dhamma thus well-proclaimed by me — clear, open, evident, stripped of rags — those monks who are Dhamma-followers and conviction-followers [18] are all headed for self-awakening. This is how the Dhamma well-proclaimed by me is clear, open, evident, stripped of rags.
http://www.accesstoinsight.org/tipitaka/mn/mn.070.than.html
and the Kitagiri Sutta.
Finally, all of them seem to be graded by Indriya:
“Bhikkhus, there are these five faculties. What five? The faculty of faith, energy, mindfulness, concentration, and wisdom. These are the five faculties. One who has completed and fulfilled these five faculties is an arahant. If they are weaker than that, one is a non-returner; if still weaker, a once-returner; if still weaker, a stream-enterer; if still weaker, a Dhamma-follower; if still weaker, a faith-follower.”
http://www.thedhamma.com/definition.htm
Last but not least, if you would like some suttic concepts of the dark night, try googling: dukkha-patipada.
Be well.