Gauges go to full tilt!?!

Sucks you're having 'fits' after getting all new stuff .. It is always a 'cluster' doing these.
No expert but I did R&R&R&solder&R ... and R&R many times to get a B body TicToc cluster.

All working and stayed that way. clapping.gif

Not 100 percent ... I think where you have 8.2 volts it should be closer to 5v.