diff --git a/api/api/cat.thread_pool.js b/api/api/cat.thread_pool.js
index 63140220b..e761b4593 100644
--- a/api/api/cat.thread_pool.js
+++ b/api/api/cat.thread_pool.js
@@ -13,7 +13,7 @@ function buildCatThreadPool (opts) {
 
   const acceptedQuerystring = [
     'format',
-    'size',
+    'time',
     'local',
     'master_timeout',
     'h',
diff --git a/api/api/indices.put_index_template.js b/api/api/indices.put_index_template.js
index 1593ddc43..3d088a83e 100644
--- a/api/api/indices.put_index_template.js
+++ b/api/api/indices.put_index_template.js
@@ -12,8 +12,8 @@ function buildIndicesPutIndexTemplate (opts) {
   const { makeRequest, ConfigurationError, handleError, snakeCaseKeys } = opts
 
   const acceptedQuerystring = [
-    'order',
     'create',
+    'cause',
     'master_timeout',
     'pretty',
     'human',
diff --git a/api/api/indices.simulate_index_template.js b/api/api/indices.simulate_index_template.js
index ae3bab82f..791806076 100644
--- a/api/api/indices.simulate_index_template.js
+++ b/api/api/indices.simulate_index_template.js
@@ -12,6 +12,8 @@ function buildIndicesSimulateIndexTemplate (opts) {
   const { makeRequest, ConfigurationError, handleError, snakeCaseKeys } = opts
 
   const acceptedQuerystring = [
+    'create',
+    'cause',
     'master_timeout',
     'pretty',
     'human',
diff --git a/api/api/reindex.js b/api/api/reindex.js
index 5712b2c56..5df290d95 100644
--- a/api/api/reindex.js
+++ b/api/api/reindex.js
@@ -20,6 +20,7 @@ function buildReindex (opts) {
     'scroll',
     'slices',
     'max_docs',
+    'prefer_v2_templates',
     'pretty',
     'human',
     'error_trace',
@@ -32,6 +33,7 @@ function buildReindex (opts) {
     waitForCompletion: 'wait_for_completion',
     requestsPerSecond: 'requests_per_second',
     maxDocs: 'max_docs',
+    preferV2Templates: 'prefer_v2_templates',
     errorTrace: 'error_trace',
     filterPath: 'filter_path'
   }
diff --git a/api/requestParams.d.ts b/api/requestParams.d.ts
index 3f8adb1b1..78e3a4ea5 100644
--- a/api/requestParams.d.ts
+++ b/api/requestParams.d.ts
@@ -243,7 +243,7 @@ export interface CatTemplates extends Generic {
 export interface CatThreadPool extends Generic {
   thread_pool_patterns?: string | string[];
   format?: string;
-  size?: '' | 'k' | 'm' | 'g' | 't' | 'p';
+  time?: 'd' | 'h' | 'm' | 's' | 'ms' | 'micros' | 'nanos';
   local?: boolean;
   master_timeout?: string;
   h?: string | string[];
@@ -825,8 +825,8 @@ export interface IndicesPutAlias<T = RequestBody> extends Generic {
 
 export interface IndicesPutIndexTemplate<T = RequestBody> extends Generic {
   name: string;
-  order?: number;
   create?: boolean;
+  cause?: string;
   master_timeout?: string;
   body: T;
 }
@@ -912,6 +912,8 @@ export interface IndicesShrink<T = RequestBody> extends Generic {
 
 export interface IndicesSimulateIndexTemplate<T = RequestBody> extends Generic {
   name: string;
+  create?: boolean;
+  cause?: string;
   master_timeout?: string;
   body?: T;
 }
@@ -1129,6 +1131,7 @@ export interface Reindex<T = RequestBody> extends Generic {
   scroll?: string;
   slices?: number|string;
   max_docs?: number;
+  prefer_v2_templates?: boolean;
   body: T;
 }
 
diff --git a/docs/reference.asciidoc b/docs/reference.asciidoc
index 5d76ef6ec..240777322 100644
--- a/docs/reference.asciidoc
+++ b/docs/reference.asciidoc
@@ -1002,7 +1002,7 @@ link:{ref}/cat-templates.html[Documentation] +
 client.cat.threadPool({
   thread_pool_patterns: string | string[],
   format: string,
-  size: '' | 'k' | 'm' | 'g' | 't' | 'p',
+  time: 'd' | 'h' | 'm' | 's' | 'ms' | 'micros' | 'nanos',
   local: boolean,
   master_timeout: string,
   h: string | string[],
@@ -1020,8 +1020,8 @@ link:{ref}/cat-thread-pool.html[Documentation] +
 |`format`
 |`string` - a short version of the Accept header, e.g. json, yaml
 
-|`size`
-|`'' \| 'k' \| 'm' \| 'g' \| 't' \| 'p'` - The multiplier in which to display values
+|`time`
+|`'d' \| 'h' \| 'm' \| 's' \| 'ms' \| 'micros' \| 'nanos'` - The unit in which to display time values
 
 |`local`
 |`boolean` - Return local information, do not retrieve the state from master node (default: false)
@@ -3317,8 +3317,8 @@ link:{ref}/indices-aliases.html[Documentation] +
 ----
 client.indices.putIndexTemplate({
   name: string,
-  order: number,
   create: boolean,
+  cause: string,
   master_timeout: string,
   body: object
 })
@@ -3329,12 +3329,12 @@ link:{ref}/indices-templates.html[Documentation] +
 |`name`
 |`string` - The name of the template
 
-|`order`
-|`number` - The order for this template when merging multiple matching ones (higher numbers are merged later, overriding the lower numbers)
-
 |`create`
 |`boolean` - Whether the index template should only be added if new or can also replace an existing one
 
+|`cause`
+|`string` - User defined reason for creating/updating the index template
+
 |`master_timeout` or `masterTimeout`
 |`string` - Specify timeout for connection to master
 
@@ -3670,6 +3670,8 @@ link:{ref}/indices-shrink-index.html[Documentation] +
 ----
 client.indices.simulateIndexTemplate({
   name: string,
+  create: boolean,
+  cause: string,
   master_timeout: string,
   body: object
 })
@@ -3680,6 +3682,12 @@ link:{ref}/indices-templates.html[Documentation] +
 |`name`
 |`string` - The name of the index (it must be a concrete index name)
 
+|`create`
+|`boolean` - Whether the index template we optionally defined in the body should only be dry-run added if new or can also replace an existing one
+
+|`cause`
+|`string` - User defined reason for dry-run creating the new template for simulation purposes
+
 |`master_timeout` or `masterTimeout`
 |`string` - Specify timeout for connection to master
 
@@ -4518,6 +4526,7 @@ client.reindex({
   scroll: string,
   slices: number|string,
   max_docs: number,
+  prefer_v2_templates: boolean,
   body: object
 })
 ----
@@ -4553,6 +4562,9 @@ _Default:_ `1`
 |`max_docs` or `maxDocs`
 |`number` - Maximum number of documents to process (default: all documents)
 
+|`prefer_v2_templates` or `preferV2Templates`
+|`boolean` - favor V2 templates instead of V1 templates during index creation
+
 |`body`
 |`object` - The search definition using the Query DSL and the prototype for the index request.