what wires are you connecting to for your grounds? Im getting weird feedback through the cluster and when I turn the headlights on the blinkers flash REAL slow, also one of the directionals come on but very dim when I turn the head lights on? also the digital odometer "flashes" when the blinkers are on...

 

Also check out shbox.com for more 4th gen LT1 wiring. Basically it looks like B3 and B15 go to ground. It may also be a power wire not hooked up.

 

Thats what I did, but depending on what "ground" wire on the 91 cluster plug I get wierd lighting issues... If I ground them both to the same ground it works better (fuel gauge doesnt cut out) but I still get the odometer to flash when the flashers are on and the turn signal comes on(dimmly) when I turnt he head lights on... I havent switched the headlight switch over to the 4th gen one yet since I wanted to work on on problem at a time... is there another power wire on the 4th gen harness that I dont know about?? ive repinned mine and the only power wires are the same ones in the picture above...

 

to help the turn signals, switch your flashers.
the hazard will help your turn signals blink faster.
as for the ground, it needs to be on the steering column, or dont bother.
its the only good source of a ground for the cluster, IMO.