(Note: this information has been provided by Charlie Baldwin.  The original is in the form of a Word document that can be downloaded by clicking Here .  Charlie's description follows:)
 

I put the pictures into a word document and added a little bit of commentary.  Sorry, some of the pics are a bit fuzzy.  Hopefully you can get the idea. You discard the bulb mount that comes with the original Lucas lamp and just glue the MR-11 spot to the back of the reflector and it is mounted to the housing when you push the chrome ring into it.  The MR-11 should be available other places, just search on the internet.  There is also one type that has a two pin mount that can be bought at Lowe's or Home Depot for low voltage accent lighting in your home.  I determined that the pins and the sockets that these use look kind of weak for something bouncing along the highway, so the bayonet mount seems better.
The wiring of the lamps is fairly simple.  The sockets have two leads, one hot and the other ground.  I grounded the one to a  bolt that I used to mount the lamp to the bracket.  The hot leads I put into black plastic harness covers (British Wiring) and ran between the gas tank and the body down below the rear splash pan on the left side where there are a bunch of bullet connectors.  There are white with brown and white with purple wires under there which are the turn signals for each side.  The turn signal relay flashes them together for the brake lights.  So all I did was replace the single female bullet connectors with double ones, solder male bullets onto my new wires and plug them.  The leads, of course were not long enough, so I spliced on some wire the correct colors purchased also from British Wiring. My TD did not come with turn signals, so when I replaced the harness many years ago, I used the harness that had turn signal wires and the dash mounted dipper switch.
As I stated to John Gunnell, I have a Signal Stat turn signal switch which has the relay to make the brake lights and turn signals all work together.
Probably this is all I will write up on this, at least until I have some more time.
A few years ago I used this same method to change the reflectors on the rear of my Austin-Healey into brake and turn signal lights.  I wrote that up and it was published in a couple of the Healey club magazines.  That is when I decided to apply the same principal to the TD.
Charlie Baldwin.

 

Images on next page.  Click Here.