Pretty sure it's Ken Ryker who's topping the twink and I'd guess it's from either the Ryker Files or Ryker's Web. If you aren't familiar with him, he's a big man - 6'4" and HUNG, and this particular scene is so hot 'cause the twink is so much smaller. I'm sure it's available on here.
Or maybe it's not him and I'm way off base…. Good luck!