This is specifically for the 2006 VH Ford Transit model but am sure my method can be used on various models.
**Note** I would like to add that in my case, the memory and main power supply were coloured in reverse? so if you find your memory is not holding, just switch these around. Because we have used a terminal block, it is super quick and easy to change wires around! No soldering or insulation tape.
Instead of Red->Red, Yellow -> Yellow, it is red->yellow, yellow-> Red.... Not sure if this was because of the loom or just a stupid Ford thing.... However either way you wire them, you will not damage your head unit.