I used 2 double contact and 1 single contact unit per side. The double contact units was used for tail light and brake light or fog light. single unit for indicators.
The expensive way is to buy the round truck taillights (not the LED type), remove the bulb holder and through away the lens. Or from a decent auto electrical shop get just the bulb holders. I've not found one in PTA area yet but there is a Breno auto electrical in kensignton near eastgate in Jhb and you can get all the stuff there . if I remember correctly the holders were something like r25 a pop.
Fir fitting them, I used a step drill (a must have for a workshop) a, a dremel with 2 cut-off disks and solder iron.
Initially i tried making the holders a push fit by removing the tabs on the bulb holder, but I wasn't happy with the fit. I then used this process. Using the step drill drill a hole big enough for the bulb and base to fit, mark the slots for the tabs/oortjies. With the dremel, router out holes(half moons really) for the tabs, not right through the base of the lens though. Now using 2 cut-off disks, cut a slot parallel to the base of the lens so that the tabs now have a place to screw into. the 2 disks give a wide enough cut. wire and off you go.
Breno can also supply connector blocks with normal spade connectors then you don;t have the fiddle with the patrols skinny ones