And here is a link that covers the full installation:
https://www.hotrodreverend.com/single-post/2018/07/22/1955-Ford-Part-58-Modern-Radio-in-the-Original-Location

enjoy

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

Melly, what is your full name? I tried to give credit to you on another site for this find, but did not have your name to mention.

Video I took during the installation

https://vimeo.com/280643336

Video I took to test after installation

https://vimeo.com/280643397

I purchased the kit that included the head unit, speaker wire, speakers, and mounting hardware. I put the speakers under the seat actually, in separate speaker boxes that I made to fit specifically. I AM IMPRESSED by the functionality and sound. Thank you so much. Let me see what I can do to post the information my ongoing thread in the This and That section.

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

I used a 6x9 in rear used original hole in center but had to drill out new hole in speaker to fit the four mounting holes. Sounds great looks great good luck. Post pictures when done.

thanks Melly, I will do that and more on a full installation. I purchased the radio you referenced, plus two speakers that went with it. I may end up going with larger speakers out back on the decklid, not sure yet. The price I paid for the unit and the two speakers was $120 shipped to my door.

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

Yes it all connects with no problems. You can connect one, two or four speaks. I used to dual voice speaker one in front 6x9 and one in rear 5x7 ( but I used 6x9 in rear had to modify mounting holes ). Works great. Post picture if you do it.

Yes it plugged right in

does the original Ford radio antenna cable plug into one of the leads on this unit?

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

Impressive. That ain't so bad at all. 

Looks great nice job.  Hope to see more pictures of other that have done this.