--- a/taskcluster/ci/config.yml
+++ b/taskcluster/ci/config.yml
@@ -1,9 +1,10 @@
 trust-domain: gecko
+project-repo-param-prefix: ''
 treeherder:
     group-names:
         'cram': 'Cram tests'
         'mocha': 'Mocha unit tests'
         'py': 'Python unit tests'
         'A': 'Android Gradle tests'
         'Fxfn-l': 'Firefox functional tests (local)'
         'Fxfn-l-e10s': 'Firefox functional tests (local) with e10s'

--- a/taskcluster/taskgraph/actions/registry.py
+++ b/taskcluster/taskgraph/actions/registry.py
@@ -172,19 +172,21 @@ def register_callback_action(name, title
         assert not mem['registered'], 'register_callback_action must be used as decorator'
         assert cb.__name__ not in callbacks, 'callback name {} is not unique'.format(cb.__name__)
 
         @register_task_action(name, title, description, order, context, schema)
         def build_callback_action_task(parameters, graph_config):
             if not available(parameters):
                 return None
 
-            match = re.match(r'https://(hg.mozilla.org)/(.*?)/?$', parameters['head_repository'])
+            repo_param = '{}head_repository'.format(graph_config['project-repo-param-prefix'])
+            revision = parameters['{}head_rev'.format(graph_config['project-repo-param-prefix'])]
+            match = re.match(r'https://(hg.mozilla.org)/(.*?)/?$', parameters[repo_param])
             if not match:
-                raise Exception('Unrecognized head_repository')
+                raise Exception('Unrecognized {}'.format(repo_param))
             repo_scope = 'assume:repo:{}/{}:branch:default'.format(
                 match.group(1), match.group(2))
 
             task_group_id = os.environ.get('TASK_ID', slugid())
 
             template = os.path.join(GECKO, '.taskcluster.yml')
 
             with open(template, 'r') as f:
@@ -193,24 +195,24 @@ def register_callback_action(name, title
                     raise Exception('actions.json must be updated to work with .taskcluster.yml')
                 if not isinstance(taskcluster_yml['tasks'], list):
                     raise Exception('.taskcluster.yml "tasks" must be a list for action tasks')
 
                 return {
                     '$let': {
                         'tasks_for': 'action',
                         'repository': {
-                            'url': parameters['head_repository'],
+                            'url': parameters[repo_param],
                             'project': parameters['project'],
                             'level': parameters['level'],
                         },
                         'push': {
                             'owner': 'mozilla-taskcluster-maintenance@mozilla.com',
                             'pushlog_id': parameters['pushlog_id'],
-                            'revision': parameters['head_rev'],
+                            'revision': revision,
                         },
                         'action': {
                             'name': name,
                             'title': title,
                             'description': description,
                             'taskGroupId': task_group_id,
                             'repo_scope': repo_scope,
                             'cb_name': cb.__name__,

--- a/taskcluster/taskgraph/config.py
+++ b/taskcluster/taskgraph/config.py
@@ -6,22 +6,26 @@ from __future__ import absolute_import, 
 
 from .util.schema import validate_schema, Schema
 from voluptuous import Required
 
 graph_config_schema = Schema({
     # The trust-domain for this graph.
     # (See https://firefox-source-docs.mozilla.org/taskcluster/taskcluster/taskgraph.html#taskgraph-trust-domain)  # noqa
     Required('trust-domain'): basestring,
+    # This specifes the prefix for repo parameters that refer to the project being built.
+    # This selects between `head_rev` and `comm_head_rev` and related paramters.
+    # (See http://firefox-source-docs.mozilla.org/taskcluster/taskcluster/parameters.html#push-information  # noqa
+    # and http://firefox-source-docs.mozilla.org/taskcluster/taskcluster/parameters.html#comm-push-information)  # noqa
+    Required('project-repo-param-prefix'): basestring,
     Required('treeherder'): {
         # Mapping of treeherder group symbols to descriptive names
         Required('group-names'): {basestring: basestring}
     },
     Required('index'): {
-
         Required('products'): [basestring],
     },
     Required('try'): {
         # We have a few platforms for which we want to do some "extra" builds, or at
         # least build-ish things.  Sort of.  Anyway, these other things are implemented
         # as different "platforms".  These do *not* automatically ride along with "-p
         # all"
         Required('ridealong-builds', default={}): {basestring: [basestring]},

--- a/taskcluster/taskgraph/transforms/task.py
+++ b/taskcluster/taskgraph/transforms/task.py
@@ -609,35 +609,19 @@ V2_L10N_TEMPLATES = [
     "index.{trust-domain}.v2.{project}.revision.{branch_rev}.{product}-l10n.{job-name}.{locale}",
     "index.{trust-domain}.v2.{project}.pushdate.{build_date_long}.{product}-l10n.{job-name}.{locale}",  # noqa - too long
     "index.{trust-domain}.v2.{project}.latest.{product}-l10n.{job-name}.{locale}",
 ]
 
 # the roots of the treeherder routes
 TREEHERDER_ROUTE_ROOT = 'tc-treeherder'
 
-# Which repository repository revision to use when reporting results to treeherder.
-DEFAULT_BRANCH_REV_PARAM = 'head_rev'
-BRANCH_REV_PARAM = {
-    'comm-esr45': 'comm_head_rev',
-    'comm-esr52': 'comm_head_rev',
-    'comm-beta': 'comm_head_rev',
-    'comm-central': 'comm_head_rev',
-    'comm-aurora': 'comm_head_rev',
-    'try-comm-central': 'comm_head_rev',
-}
-
 
 def get_branch_rev(config):
-    return config.params[
-        BRANCH_REV_PARAM.get(
-            config.params['project'],
-            DEFAULT_BRANCH_REV_PARAM
-        )
-    ]
+    return config.params['{}head_rev'.format(config.graph_config['project-repo-param-prefix'])]
 
 
 COALESCE_KEY = '{project}.{job-identifier}'
 SUPERSEDER_URL = 'https://coalesce.mozilla-releng.net/v1/list/{age}/{size}/{key}'
 
 DEFAULT_BRANCH_PRIORITY = 'low'
 BRANCH_PRIORITIES = {
     'mozilla-release': 'highest',