Remap really helped mine
http://www.alivetuning.com/vehicles-defender/
Replace the small side lights, rear lights and indicators with decent sized NAS ones
http://www.rimmerbros.co.uk/Item–i-GRID012671
Rear work lamp was handy for night rides, had a switch for it on dash as well, handy for reversing and when someone was tailgating at night….
If you search it is likely that there is wiring for rear reversing light on the other side from single light, an easy job to wire up another one to give twin reversing lamps
http://www.macmillan4x4.co.uk/Photos/landy12.html
Rear wheel carrier if don’t want to wreck rear door
Side impact protection is rubbish, fit something sturdy.
http://www.paddockspares.com/pm736-tree-sliders-pair-defender-90-black-powder-coated-over-zinc-plate.html
Can get heated mirror kits
I actually fitted larger mirrors which were helpful on continent
http://www.paddockspares.com/pm752-door-mounted-mirror-defender-large-type-web-exclusive-special-offer.html
Door latch forever catching on trousers and always catches seatbelt
http://foundry4x4.co.uk/index.php?route=product/product&product_id=68
Get rid of egr valve
http://www.alivetuning.com/wp-content/uploads/2014/02/EGR-bypass-kit.pdf
Lockable cubby box?
Fit extra 12 volt accessory sockets on dash and/or cubby box
Cooker housing on rear door?
There’s loads of things you can do to adapt it to your needs and can be a bit of a money pit too…..
Here’s mine
http://www.macmillan4x4.co.uk/vehicle.html