Dash speakers are 3 1/2 inches. They are a real pain to replace. You need to remove all lower portions of the dash.
The speakers i put in the dash of my 98 were 3.5 inch speakers!
dash lights relay
6 1/2 inch speakers on all four doors and 4x6s in the dash
the fronts are 4x6 and the rears are 6x5
6 x9 in the back and 3.5 inch round ones in the dash ........tuner1978
2- 3 1/2"s in the dash 2- 4x10"s in the rear
Oldsmobile Curved Dash was created in 1901.
left of the console area under left side of dash. Rick ASE L-1 Master TransMichigan.com
I have the factory repair manual -- looks like the socket is under the dash just left of center. Not sure how easy it is to get hand on it.
There are no dash speakers.Just 6.5" door speakers and ~1.25" tweeters.
A '99 Olds Delta 88 doesn't use an orifice tube system for the air conditioning it uses a thermal expansion valve. The location is under the passenger side dash in the heater/evaporator box. Unfortunately, you have to remove the dash to replace it as well as discharge the a/c system.
The flasher for the 1996 Oldsmobile Delta 88 is located under the dash on the left hand side. Remove the plastic kickpanel that houses the fuse box by removing three screws and one wing nut on the firewall left of the brake petal.the Flasher is clipped on the upper side of that plastic kick panel.