diff --git a/toolkit/components/telemetry/Histograms.json b/toolkit/components/telemetry/Histograms.json
index c5a7793ee997..b6bd41ce4655 100644
--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -53,28 +53,6 @@
     "high": 60000,
     "n_buckets": 50
   },
-  "ADDON_CONTENT_POLICY_SHIM_BLOCKING_LOADING_MS": {
-    "record_in_processes": ["main", "content"],
-    "expires_in_version": "58",
-    "kind": "exponential",
-    "high": 60000,
-    "n_buckets": 20,
-    "keyed": true,
-    "description": "The amount of time the content process blocked processing shouldLoad shims for an add-on (keyed by add-on ID) prior to the load event, for each document load.",
-    "bug_numbers": [1331684],
-    "alert_emails": ["kmaglione@mozilla.com"]
-  },
-  "ADDON_CONTENT_POLICY_SHIM_BLOCKING_LOADED_MS": {
-    "record_in_processes": ["main", "content"],
-    "expires_in_version": "58",
-    "kind": "exponential",
-    "high": 60000,
-    "n_buckets": 20,
-    "keyed": true,
-    "description": "The amount of time the content process blocked processing shouldLoad shims for an add-on (keyed by add-on ID) after the load event, for each document load.",
-    "bug_numbers": [1331684],
-    "alert_emails": ["kmaglione@mozilla.com"]
-  },
   "ADDON_MANAGER_UPGRADE_UI_SHOWN": {
     "record_in_processes": ["main", "content"],
     "expires_in_version": "53",
@@ -13473,6 +13451,16 @@
     "n_buckets": 100,
     "description": "The amount of time it takes to perform a set via storage.local."
   },
+  "EXTENSION_UPDATE_TYPE": {
+    "record_in_processes": ["main"],
+    "alert_emails": ["addons-dev-internal@mozilla.com"],
+    "bug_numbers": [1460336],
+    "expires_in_version": "66",
+    "kind": "categorical",
+    "labels": ["JSON", "RDF"],
+    "releaseChannelCollection": "opt-out",
+    "description": "The type of update manifest served for a given update request."
+  },
   "NOTIFY_OBSERVERS_LATENCY_MS": {
     "record_in_processes": ["main", "content", "gpu"],
     "alert_emails": ["nika@thelayzells.com"],
diff --git a/toolkit/components/telemetry/Scalars.yaml b/toolkit/components/telemetry/Scalars.yaml
index 57ff6d9a7df6..756ee11995e8 100644
--- a/toolkit/components/telemetry/Scalars.yaml
+++ b/toolkit/components/telemetry/Scalars.yaml
@@ -381,6 +381,20 @@ browser.session.restore:
     record_in_processes:
       - 'main'
 
+extensions.updates:
+  rdf:
+    bug_numbers:
+      - 1460336
+    description: >
+      The number of RDF update requsts for a given extension ID.
+    expires: "66"
+    kind: uint
+    keyed: true
+    notification_emails:
+      - addons-dev-internal@mozilla.com
+    record_in_processes:
+      - main
+
 # This section is for probes used to measure use of the Webextensions storage.sync API.
 storage.sync.api.usage:
   extensions_using:
diff --git a/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm b/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm
index 62fe10142778..75b1f2ac6626 100644
--- a/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm
+++ b/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm
@@ -41,6 +41,8 @@ const LOGGER_ID = "addons.update-checker";
 // (Requires AddonManager.jsm)
 var logger = Log.repository.getLogger(LOGGER_ID);
 
+const updateTypeHistogram = Services.telemetry.getHistogramById("EXTENSION_UPDATE_TYPE");
+
 /**
  * Sanitizes the update URL in an update item, as returned by
  * parseRDFManifest and parseJSONManifest. Ensures that:
@@ -295,8 +297,11 @@ UpdateParser.prototype = {
                     "and support will soon be removed");
 
         json = UpdateRDFConverter.convertToJSON(request);
+        updateTypeHistogram.add("RDF");
+        Services.telemetry.keyedScalarAdd("extensions.updates.rdf", this.id, 1);
       } else {
         json = JSON.parse(data);
+        updateTypeHistogram.add("JSON");
       }
     } catch (e) {
       logger.warn("onUpdateCheckComplete failed to determine manifest type");