The hitch and galvanized backing plate are only for attachment directly to a bumper, IE camel style mantec fronts or the special vehicles discovery rear bumpers.

You are using the RN hitch adapter and so do not need the backing plate (not bolting through a bumper or steel plate). Remove the galvanized plate, set aside for if you ever do a bumper mount, or need to sell the tow jaw. Front part of jaw will bolt directly to hitch receiver piece.

 

 

That probably bolts to the rear bumper on uk models, i have a uk rear bumper on mine , i had to ,odd the bumper since uk trucks dont have the reciever hitch

 

 

3.5 ton jaw (2 bolt) is for front bumper

5 ton jaw (4 bolt) is for rear bumper

The factory rear bumper is NOT strong enough. Camel's which used the 5ton hitch were fitted with different bumpers unique to those cars, not the factory ones. For comparison just google camel trophy discovery and check those bumpers to say a normal discovery.

EDIT: the factory bumpers for camel might have only been modified in the center portion with a big welded insert, but now I cannot recall.

Defender rear cross member however has provisions for the 4 bolt style hitches either nato eyelet type or dixon bate pin type, which also need backing plate

 

My uk bumper came with a steel plare that had nuts welded to it that got welded to the rear crossmember behind bumper, 4 bolt holes in bumper in middle, should be pics in my build thread towards the end

 

my 97 d1 came with a tow hitch package and i've towed a jet ski but i'm curious as to how big of a trailer i can tow [like a 22' airstream] what are the d1's capacity,thanks

 

 

that is a nice hitch,i thought i read somewhere d1's only have a towing capacity of 2200lbs,but it's nice to know i can pull more,5500 should be enough for a decent trailer [hopefully uphill!! in the mountains]