diff --git a/beets/autotag/__init__.py b/beets/autotag/__init__.py
index 3e79a4498..822bb60ef 100644
--- a/beets/autotag/__init__.py
+++ b/beets/autotag/__init__.py
@@ -157,3 +157,5 @@ def apply_metadata(album_info, mapping):
             item.composer = track_info.composer
         if track_info.arranger is not None:
             item.arranger = track_info.arranger
+
+        item.track_alt = track_info.track_alt
diff --git a/beets/autotag/hooks.py b/beets/autotag/hooks.py
index 40db6e8d3..3c403fcf4 100644
--- a/beets/autotag/hooks.py
+++ b/beets/autotag/hooks.py
@@ -145,6 +145,7 @@ class TrackInfo(object):
     - ``lyricist``: individual track lyricist name
     - ``composer``: individual track composer name
     - ``arranger`: individual track arranger name
+    - ``track_alt``: alternative track number (tape, vinyl, etc.)
 
     Only ``title`` and ``track_id`` are required. The rest of the fields
     may be None. The indices ``index``, ``medium``, and ``medium_index``
@@ -154,7 +155,8 @@ class TrackInfo(object):
                  length=None, index=None, medium=None, medium_index=None,
                  medium_total=None, artist_sort=None, disctitle=None,
                  artist_credit=None, data_source=None, data_url=None,
-                 media=None, lyricist=None, composer=None, arranger=None):
+                 media=None, lyricist=None, composer=None, arranger=None,
+                 track_alt=None):
         self.title = title
         self.track_id = track_id
         self.artist = artist
@@ -173,6 +175,7 @@ class TrackInfo(object):
         self.lyricist = lyricist
         self.composer = composer
         self.arranger = arranger
+        self.track_alt = track_alt
 
     # As above, work around a bug in python-musicbrainz-ngs.
     def decode(self, codec='utf-8'):
diff --git a/beets/autotag/mb.py b/beets/autotag/mb.py
index da286332f..a0d4dc33a 100644
--- a/beets/autotag/mb.py
+++ b/beets/autotag/mb.py
@@ -269,6 +269,7 @@ def album_info(release):
             )
             ti.disctitle = disctitle
             ti.media = format
+            ti.track_alt = track['number']
 
             # Prefer track data, where present, over recording data.
             if track.get('title'):
diff --git a/beetsplug/discogs.py b/beetsplug/discogs.py
index cf10a2a36..3b3f5f201 100644
--- a/beetsplug/discogs.py
+++ b/beetsplug/discogs.py
@@ -314,7 +314,9 @@ class DiscogsPlugin(BeetsPlugin):
             # Only real tracks have `position`. Otherwise, it's an index track.
             if track['position']:
                 index += 1
-                tracks.append(self.get_track_info(track, index))
+                track_info = self.get_track_info(track, index)
+                track_info.track_alt = track['position']
+                tracks.append(track_info)
             else:
                 index_tracks[index + 1] = track['title']
 
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 4e0d7405f..eaf8c7d5a 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -8,6 +8,11 @@ New features:
 
 * Added support for DSF files, once a future version of Mutagen is released
   that supports them. Thanks to :user:`docbobo`. :bug:`459` :bug:`2379`
+* The MusicBrainz backend and  :doc:`/plugins/discogs` now both provide a new
+  attribute called ``track_alt`` that stores more nuanced, possibly
+  non-numeric track index data. For example, some vinyl or tape media will
+  report the side of the record using a letter instead of a number in that
+  field. :bug:`1831` :bug:`2363`
 
 Fixes:
 
diff --git a/test/test_importer.py b/test/test_importer.py
index 500ca027d..87724f8da 100644
--- a/test/test_importer.py
+++ b/test/test_importer.py
@@ -1723,6 +1723,7 @@ def mocked_get_release_by_id(id_, includes=[], release_status=[],
                         'length': 59,
                     },
                     'position': 9,
+                    'number': 'A2'
                 }],
                 'position': 5,
             }],
diff --git a/test/test_mb.py b/test/test_mb.py
index ecbcf3c59..ca1bf2a1a 100644
--- a/test/test_mb.py
+++ b/test/test_mb.py
@@ -68,6 +68,7 @@ class MBAlbumInfoTest(_common.TestCase):
                 track = {
                     'recording': recording,
                     'position': i + 1,
+                    'number': 'A1',
                 }
                 if track_length:
                     # Track lengths are distinct from recording lengths.
@@ -182,6 +183,7 @@ class MBAlbumInfoTest(_common.TestCase):
         second_track_list = [{
             'recording': tracks[1],
             'position': '1',
+            'number': 'A1',
         }]
         release['medium-list'].append({
             'position': '2',
@@ -454,6 +456,7 @@ class MBLibraryTest(unittest.TestCase):
                                     'length': 42,
                                 },
                                 'position': 9,
+                                'number': 'A1',
                             }],
                             'position': 5,
                         }],