[mr48chev]

As Nvrdone mentioned in post 3 changing the sockets to take a 1157 bulb or the brighter one (2357) that fits the same socket.

You have to have the right turn signal switch that lets the brake lights work though the turn signal switch. A lot of those old add on at the dealer switches only worked the turn signals and you had to have an extra light on the rear for the turn signals as the brake lights still worked though the stock tail lights.

The park lights can be modified to put in a socket for 1157 bulbs in the front so that you have park and turn in those lights and don't have to add extra lights.

One thing I found on my 48 and my 71 is that painting the inside of the tail light or park light housing bright white works a lot better than having it silver or the black that some of them come with. That makes a big difference with both stop/turn and tail light brightness.