Swapping out non working speedo/adding a radio

The factory dash speaker was in a support frame that was held up with 2 of what are called keyhole studs. The keyholes are hidden under the defrost vents. I don't know what you'll find in a radio delete build. Don't know what retrosound provides either. I guess you will find the radio plug in the wiring harness. It might be taped down/away but in the general area somewhere. It will have a red wire and a orange wire. Green and black to speaker come out of the radio. Factory simply switched up the male and female terminals to keep speaker polarity correct. All of it was chassis grounded.
I would clean and lube the speedo cable and clean the square drive input port of a used speedo too. Clean all contact points on circuit boards? As much as 40 bucks for all new high quality bulbs and sockets? The more you do now the less frequently you'll be going back in. It took almost 4 years for my cheap ebay Chinese bulb socket mistake to show itself.