How to wire newer style lights to my 1970 VW bug?

I have a 1970 vw bug. I'm installing newer tail light assembly on it. The new lights are for a 1940 Ford. What my problem is I can't get the turn signal and brake lights to work together. I can get tail lights and turn signals but no brake lights. I can get tail lights and brake lights to work but no turn. I have 5 wires in the rear from the vw. The new light has 3. What am I doing wrong. Thank you very much.How to wire newer style lights to my 1970 VW bug?I'm not sure they're compatible. The 1940 Ford only had one bulb for brake light, turn signal, and tail light. A 1970 VW had three bulbs. One for tail light/brake light, a second for the turn signal, and a third back-up light. If you can install a second bulb holder and bulb in the Ford light housing you can use one for the turn signal and the other for the tail/stoplight and not have backup lights.