T-5s will definately work. They are a common swap because they have lots of fun low in the gears and have an OD that saves on gas. Search a little here and you'll find several threads on the topic. There was one thread that specifically listed and discussed all the parts needed to do the swap.

 

I swapped from a 65 "Falcon Style" sweep instrument panel over to the GT or 66 style 5 Dial Gage cluster. There's a page on my site that explains how to do all the wiring. A couple of years later, I pulled that gage cluster out and replaced it with Autometer gages below. I picked up the Artic White Autometers off Craigs list, bought a new bezel and an aftermarket gage holder from Dallas Mustang, and installed.




(and yes the dash is crooked, I just set it in there for the photo)

 

fwiw here's a link to a large pic of my stock '65 interior.
(ok, the radio ain't stock, but I DO have the stock one sitting on a shelf in the garage. It (pushbutton AM) was ordered as an option.
http://img.photobucket.com/albums/v3.../image0-10.jpg

Lotta red there.

 

I saw the page regarding the swap. I tried to go to mustangsteves page to see how I would do it since I have power assisted drums.However, the link is invalid. Do you have a guide on that?

-Rick

I can't decide whether I want to clean up the old dash cluster or just buy/build a new one. Hmm