@ the Berd and Bob S.

The link was attached earlier bit if you are using the original radio make sure you don't "over-cook it" with the new speaker technology.

".... Note: Many replacement speakers now sold by the discount stores, auto parts stores and mail order restoration parts houses are labeled as "4 to 8 ohm compatible" and are in fact 4 ohm speakers. These speakers can damage the older transistor radios. 4 ohm speakers will measure around 3.2 ohms with a DC ohmmeter. An 8 - 10 ohm speaker will measure around 7.4 ohms with a DC ohmmeter. The DC resistance is the critical number for the Delco radios as the output transistor is in series with the speaker. A properly operating Delco radio should have 1.5 volts DC across the speaker voice coil. A 4 ohm speaker will draw twice the current of an 8 ohm and cause the amplifier transistor (the half dollar size device mounted to the black finned heat sink on the back of a Delco radio) to run very hot. The speaker cone should be displaced in an upward (away from the magnet) direction about 1/8" when a Delco radio is turned on. If the cone moves down toward the magnet, the speaker leads need to be reversed. Ford and Chrysler radios of the period used the same type of germanium output transistors as the Delco radios and also require 8 ohm speakers. However, Ford and Chrysler radios ran with 0 to 1 volt DC offset on the speaker depending on the radio model and vintage. Many will not deflect the cone when turned on like the Delco radios.

Warning: Never run 4 ohm speakers on any vintage car automobile radio using transistor output circuits...."