How do I remove the radiator on a w140

[pokeyarw]

I've removed lots of radiators on my previous MBs but, as is indicated in most of the posts, they have been held in with clips, which made removal easy. My '92 300SD has some kind of plastic posts on the top which fit in holes in the frame. It appears to sit in holes in the bottom frame, so I obviously have to release something, but I can't see how it all comes out. I'd appreciate some instruction.

BTW, it's running hot when under load (hill climbing) and I want to look between the A/C condenser and radiator or crud, before I get to some really drastic remedies. I've already flushed it with no apparent result.
instruction.
Thanks, ARW