[oldengine]

Find in postbit template:

<if condition="$post['replylink']">
	<a href="$post[replylink]" rel="nofollow"><img src="$stylevar[imgdir_button]/<if condition="$post['forwardlink']">reply_small<else />quote</if>.gif" alt="$vbphrase[reply_with_quote]" border="0" /></a>
</if>

Replace with...

<!-- Start last post reply Hack -->

<if condition="$post['islastshown'] AND $post['replylink']">
<a href="$post[replylink]&amp;noquote=1" rel="nofollow"><img src="$stylevar[imgdir_button]/reply_small.gif" alt="$vbphrase[reply]" border="0" /></a>

<else />

<if condition="$post['replylink']">
<a href="$post[replylink]" rel="nofollow"><img src="$stylevar[imgdir_button]/<if condition="$post['forwardlink']">reply_small<else />quote</if>.gif" alt="$vbphrase[reply_with_quote]" border="0" /></a>

</if></if>
<!-- End last post reply Hack -->