The areas circled are where I cut the original circuit board. Connections need to be such that ultimately all the bottom pin represents the signal, and the LED body goes to ground. Looking at this cluster, where the lighting plug connects to it, the third connection from the bottom is the earth connection.
Looking at this photograph does not show what I have done very well, so a verbal explanation too. For identification purposes, bulb 1 - top left, bulb 2 = top right, bulb 3 = bottom left, bulb 4 = bottom centre, bulb 5 = bottom right.
Bulb 1 bottom pin connects to plug pin 2 (from the top)
Bulb 2 bottom pin connects to plug pin 1 (top)
Bulb 1 & 2 outer body connect to each other and to plug pin 3 (3rd from top) - car earth
Bulb 3 bottom pin, no change as it is correct, connected to plug pin 4 (4th from top)
Bulb 4 bottom pin connects to plug pin 5 (5th from top)
Bulb 5 bottom pin connects to plug pin 6 (bottom)
Bulb 3, 4, 5, outer body connect to each other and plug pin 3 - common to car earth
The earth connections bridge over the links between Bulb bottom pins and plug pins.
LEDs were bought from www.crazyleds.co.uk, using the same numbers as originals, ie 501, 382, etc. I used 21W red equivalents for brake lights and fog lights, yellow for indicators, and white for reversing lights. A 5W equivalent red LED was used for rear light. When you come to getting yellow ones for the indicators, make sure you check whether the ones in the car are offset pin and/or opposite pin type.