Help with heater core replacement-'87 5kTQ

[Tony Lum <tlum@flash.net>]

Hi gang,

I'm trying to replace the core in my heater box assembly.  Getting the
assembly out of the car wasn't too bad, but getting the box apart has been
a royal PITA.  I've removed the clips all around and the two deep screws in
the recess in the middle of the assembly, but it still won't split apart.  

Is there a trick to this or should I continue to nurse it apart?  Do you
really have to dismantle all the flap levers?

My thanks in advance,

Tony

1987 5000 Turbo Quattro, heaterless for now.