Prosilver Location: In viewtopic_body.html around line 305, above
<!-- INCLUDE jumpbox.html -->
Subsilver Location: In viewtopic_body.html around line 332, above
<!-- INCLUDE breadcrumbs.html -->
Explanation: So extensions can add content to the bottom of topic pages. For example, my Precise Similar Topics MOD inserts the similar topics here. I also believe Evil Quick Reply MOD inserts at this location too. The location is after the Post Reply, Quick Reply and post sorting buttons, but prior to any breadcrumbs, MOD tools.