[68K30]

Find a 1985 or in that general age gas, not diesel gm truck or suburban and remove the brake light switch, the vacuum switch (on the firewall by the brake booster) you really need the vacuum switch, the harness connecting the two that goes down to the trans( has the plug for the trans) hook up one switched power wire and you have the whole correct GM system. I did it to my 68,only cost $15.00 and really simple.

Hope this helps
Bill