Hey "madmat" chances are you have the c-6 with that 351w. If you can't tell, let me know I can get you pictures of both a c-4 and a c-6 ! Next, what questions do you have ? Also, this swap is easy but with a 351w you may have hood cleance issue's depending on what intake, carb, and air cleaner you are useing or if it's fuel injection you want. Check out my web pages for more details :
index ,.....I would recommend the c-4. As the c-6 will eat up lots of H.P. and you will need a custom drive shaft. The c-4 can stay stock or you can get them beeffy, some 70'S LTD's had 351w with c-4's so you can find the bellhousing, fly wheel, Torqconverter, and etc... The c-6 is longer and wider then a c-4. You also need to deside on what you want to do about the k-member, you can use the one you have but there is some other choices. The trans. tunel on ALL Fairmonts / Zyphers are the same for both automatic and manual, and as far as I remeber so did the Stangs between '79-'85 for sure after that I do not know. ....Many more things we can talk about, but lets start here. Good Luck !