Blogger headings conditions on Index and Item pages

On Blogger I have a <class="subheading"> which I have applied to all <h2> on the item page, however on the index page, I need the <class="subheading"> to be for <h3>.

This is the codes I'm using but it doesn't work

code 1

<b:if cond='data:blog.pageType == &quot;index&quot;'> 
 <h3 class='subtitle' itemprop='name'></h3>
<b:else/> 
 <h2 class='subtitle' itemprop='name'></h2> 
</b:if> 

code 2

<b:if cond='data:post.body'> 
 <b:if cond='data:blog.pageType == &quot;index&quot;'> 
  <h3 class='subtitle' itemprop='name'></h3>
 <b:else/> 
  <h2 class='subtitle' itemprop='name'></h2> 
 </b:if> 
</b:if>