I have the TCP manual Rack & Pinion and if I were to do it over, I would rebuild the stock system. I have posted my thoughts on this before, so I just copied and pasted the information below.
First off I'm not trying to bash TCP. I have many of their products on my car and feel that they are all top quality and very well engineered for our cars. I just feel that the rack and pinion is not that drastic of an improvement to warrent the $$. The TCP system is a very quality piece and the steering is very precise. But the steering effort is very high, especially at low speeds and your turning radius is increased. I had no idea that the TCP R&P system increased my turning radius until I tried to park.
The biggest problem with the steering on our cars is a 30+ year old steering box, but now that you can get a new steering box with a needle bearing design, I don't see the need to convert to R&P.
If I were to do it all over again, I would go with the Flaming River box - http://www.flaming-river.com/ . The Flaming River steering box will decrease the steering effort and provide slop free steering and the 16:1 ratio is a quicker ratio then the stock steering box.
You can get the Shelby idler and pitman arms which increase the responsiveness of the steering (but also increase steering effort). Cobra Automotive - http://cobraautomotive.com/ - has them with pressed in bearings which should help to reduce steering effort.
And in the current Mustangs and Fords magazine, in the new products section, someone is advertising tie rod ends with a hemispherical bearings. When I get home, I'll check the add and see if there's a link.
All in all I believe this would provide an early model Mustang with a very responsive, slop free steering at a reduced steering effort while maintaining the turning radius.
This poll mentions TCP and Flaming River. What other brands are out their for a 66? Flaming River doesn't make one for the 66 unless you have a Mustang II front setup. Im in the process of swaping mine out so any passed on experience would be helpfull.
I want power steering on my car but i don't really care for the prices on R&P sets. What do i need to do to my 200 to put on power steering? Does anybody make an entire kit to converte a 6 cyl M/S to a 6 cyl P/S????Prices???
flaming river has major issues, very few people have had any luck at all with them, they don't fit with headers, there are major bumpsteer issues and they apparently didn't do any engineering at all with them, i'd go with randall's rack check it out at www.randallsrack.com thats the rack i'll be using once i get the money saved up