Pics are below.  I have had so many inquiries on how I built this model that 
I have decided to put the explanation here for all to see.  Good Luck!

So assemble an IG sentinel as per normal.  Cut off the top of the roll cage
and glue 3 pieces of sprue to the inside of the cockpit a bit above the
level of where the top of the cage was.  Glue the top portion of the Leman
Russ turret to the three pieces of sprue.  Add the vindicator extra armour
to the legs by simply setting them over the top ridge ot the hip joint.  Add
the vindicator extra armour to the turret so that the the long portion is
flush to the long portion of the turret.  It actually fits perfect by
hooking the short portion around the angle of the turret.  Hook another
vindicator plate over the back portion of the turret to form the stairs.
Glue the LR exhaust ports to this plate.  On the side opposite the lascannon
add half of the metal mount from the LR demolisher [from the sponson] to the
vindicator plate.  Place the Land Raider Smoke launchers just infront of
that.  In the center of the turret at the front add the vindicator sensor
array.  At the front glue a lascannon shield form the Land Raider to the
front of the cannopy of the sentinel.  I think i had to add some greenstuff
to give it a flat area to adhere to since the front of the sentinel is
angled.  Then insert a piece of plastic card into the gap of the turret so
that it just touches the lascannon shield you just added.  Ontop of the
plastic card add the missile pod from the SM Dread.  Add a small piece of
plastic card for the extra armour plate just below the missile pod to glue
to.  To the underside of the seninel body glue the air intake vent from the
back of the Leman Russ.  Add the extra armour plates to the sides of the
legs, sides of the lascannon shield at the front, and rear portion of the
turret attached to the vindicator plates attached there.  To the sentinel
legs add the SM Dread shin guards and  attach the warlord titan feet with
pins.  The lascannon is attached to the side via a large tank wheel from the
LR tread sprue.   I then glued the Twin-linked lascannon from the SM Dread
to the wheel [I used a pin here as well].  On the lascannon is a single
piece of extra armour and the small vent from the Leman russ.  I then added
two wires for the cables running out the back of the cannon.