Identify the Wiring
Just a little information to get us started. The Lucas unit removed had 4 wires to that unit. My wires had been changed and replaced over the years and I do not have exact color matching for them, but I think I can explain how to do this installation with good results. 

You should be able to determine the very large power wire that feeds the battery. The second wire is the ground wire; on the Lucas it is the wire on the extreme right side of the Lucas unit. There should now be two wires off of the Lucas unit to identify. Take a Digital Multi Meter (DMM) and attach the positive lead to the end of one wire and the other lead to a good ground source, set the meter to measure 12 volts (V) and then turn the ignition key to the “ON” position. If the DMM reads 12V this wire is then the wire to attach to the “L” spade on the #14255 alternator. The other wire will go to the other spade on the #14255, and attach to right side spade, inside the only cutout on the back of the #14255. 

Mounting
The #14255 attaches to the original engine bracket using a long grade 8 bolt & necessary washers and “tube spacers” as shown below, this installation requires 2 of these tube spacers to keep the alternator from twisting or yawing in the bracket. 

The adjustable arm that attaches to the top of the water pump is a off the shelf item from the auto parts store, it had to be cut and redrilled for fit & function. I had to cut 2 pieces off the arm to get it to fit. The arm also had to be shaved where it comes into contact with the alternator fan. 

The pulley on the #14255 is the supplied pulley that came with the alternator. It has a flat side as part of its Inside diameter to fit the alternator shaft. The pulley is of the split design, in other words the pulley is made up of two pieces. To better fit the width of the standard grooved fan belts I added washers, spacers, between the pulley halves to spread them apart to better accept the belt. When assembling all of the pulley parts, locktight, blue, was used on the shaft nut and shaft & spacers. 

KoolKat is not using the spring-loaded adjustment pulley that is original to the car. Because of the diameter of the alternator pulley and its case size, the longest belt needs to be used and I believe this to be # 09-0117 of the XK # 12 catalog page 152. (800-444-5247) 

The above photo shows the back of the #14255 alternator. The power wire is the wire with the blue spacer on the top right side of the alternator. The “L” spade has the yellow connector and the wire as described earlier. The other wire is attached to the other spade connector in the same cutout. Ground wire is located on a screw into the case at the lower left side of the alternator.

The above photo shows a close up of the bracket & spacers, and of course the grade 8 bolt through the assembly. Notice that the bracket is black and the spacers are on each side of the bracket, this is done to align the alternator pulley groove with the water pump pulley. 

The above photo shows a close up of the bolt head and the tube spacers and engine bracket. Be very careful of the tension on the flanges of the alternator, the spacers are to be cut to take up the space between the engine bracket and the alternator flanges, over tightening the bolt may, could, break the aluminum style alternator flanges, not good. Also notice the addition of a yellow colored “sleeve” in the engine bracket & bolt tube, this is in place to take up space of the inside diameter of the bracket and the tube spacer that the bolt goes through. All of the hardware, bolt & nuts pulley washers were available at a local hardware store, just take your time and plan on trying items and refitting to get it right & tight. 

The above photo shows a front view of the alternator, notice the adjustable arm and see how close the arm comes to the fan, this is where it had to be shaved for clearance. Notice how well the belt fits into the pulley.  Hey, how about that engine breather air filter, K&N of course, using water pump to intake manifold hose. 

The above photo shows the distance spread of the pulley. 

Total cost of alternator & adjustable arm at Checker’s Auto Parts, lifetime warranty, tube spacers & grade 8 bolt etc. was less than $100 and I did not turn in the Lucas unit but paid the core charge & kept the old unit.  Mike Goodwin & KoolKat in Phoenix.