66 Rear End

Hey. I'm currently 15 and have been restoring my first mustang. It's a 66 and the project has been taken upon mostly by myself where I probably know more about cars than my dad ha ha. The mustang currently has a straight six engine and I want to upgrade the engine to a 289 or possibly a v8 5.0 from a later mustang. I have been looking in to what to do for the rear end, and at this point i am almost clueless. I have read that a granada or versailles rear end will work for the mustang but the gears are only geared around 2.50 to about 2.89. I was hoping to have the gears be around 3.5 to get more low end power out of the stang. How hard would it be to convert a granada or versailles rear end to a lower gear around 3.50? How much would this be cost wise and would it be something i could do on my own or would i need to have someone else do this? Also, is there any way i could do this another way that would save me some money where my budget is quite low? I have been watching the local classifieds for the past couple years and i have only seen a couple rear ends pop up for the 65-66 mustang so that idea doesn't seem that possible right now. Any help or ideas would be appreciated...
Thanks  

You can buy the "short' 9 inch rear axle housing for the early '66 'stang already made to fit your existing leaf spring/brake set-up. The rear end out of later model Mustangs like '67-72 needs to be shortened about an inch to be used in the earlier models. After that you can buy and instal any 9' rear end differntial and ratio you want. They are readily available and pretty easy to instal.
The standard 8 inch rear end for all but the hipo motor works good on stock motors and even mild street performance set-ups. Once you go over 300 HP with the intent to thrash the pony then 9 inch might buy you a little extra insurance.  

The Ford 8" and 9" rear ends are known as the poor mans quick change because they have removable third members. All thats required is that you pull the axles out a foot or so and then remove the third member and replace it with whatever third member you buy from the swap meet(no further setup necessary). 3.5:1 rear gears are popular in both 8 and 9 inch rears, but you might come across an 8 inch third member as low as $150 or so. Locker or limited slip gears cost more of course. 8 inch rearends are still fairly easy to come by and as Jbirch says be aware that the early mustang uses a narrower rear housing(banjo housing). IMHO an 8 inch can be used up to 400 hp or so depending on how nasty you are with the clutch, they are pretty tough. If you use a standard C4 or four speed then the 3.5 gear is about right, if you go to a Tremec with overdrive then a 3.8 or a little higher is perfect. See http://www.carnut.com/specs/rear.html for rear end widths.  

Do you have any recommendations as to where to pick up a ford rear end? I have been watching the local classifieds for quite a while and have only seen a couple pop up and they usually go pretty quick! You say they are easy to come by, but i just don't know where else to look... Also, do you know where i could purchase a third member for a reasonable price?
Thanks  

the 57-59 ford car rear is a perfect bolt in fit for the 65-66, they were all 9" and i used one once, be sure to use the brakes cause the bearings are larger and get the spring plates to. in mississippi at the time you got your permit at 14.5 and you took the driving test at 15. i got my first car which was a 66 stang at age 15 i'm 52 now. that 66 needed an engine , the 3 speed manual trans was stripped and it needed front end and brakes and even though my dad grew up on a farm and worked on eveything from tractors to hay balers when he was growing up he said if i wanted it to run it was up to me to fix it. i used his tools and went at it and have ben doing it ever since. after i blew the 8" someone told me about the 57-59 9" rear and i decided to learn to set up my own ring and pinion and installed a 3.25 traction-loc and i was barely 16. 15 years is not too young to do this stuff.when i was 17 i worked at the local texaco service station after school and on weekends and summer doing tune-ups ,oil changes , water pump replace , brake jobs. frist thing to do is get a 66 ford shop manual and go for it ! as for the 57-59 rear end look on the web or have the local salvage yard do a search you could check e-bay but i dont know if they have an age requirement to register. NOTE> check this web site www.ultrastang.com and click on the INFO section FORD 9" REAR END INFO > THE FORD 9" REAR END this site has all the info on 65 and up mustang rear ends including the 57-59 rear end.  

Thanks for your encouragement. Most people just think I'm crazy to be spending all my time on money on an old car this young so it's funny to see what other people think. I got the car a year and a half ago and i really enjoy it. I have a few shop manuals to try to help me but they don't always work the best. It's usually the internet that helps me ha ha But anyways, I just sent an inquiry for some salvage yards and am looking on ebay right now to see if i can find anything... I think now knowing that i can switch out the 57-59 rear end might help a little bit. I'm not sure how many there are out there, but i'll see what i can find. Thanks for your help  

Ashton I would look on craigslist and at local swap meets. Most of the swap meets I go to have ten or twelve of the 8 or 9 inch pumpkins(third members) sitting around. I have seen them for varying prices for sure. I see one assembly on ebay with discs on it that hasnt bid past $300 yet,,item 150383417941. So just keep your eyes open and you will find them.  Dont get confused the 8 and 9 inchers look alike but the 9 incher is much stronger and the 8.8 inch unit is a newer design. Good luck.  

Hang in there buddy!  Welcome to the wonderful world of working on old cars! You might want to ask (and answer) a couple of questions to yourself.  1) What do you want a quick solution to get it rolling or are you building for a long term project? 2) What do you see the future of the car (keep for a long time 10+ years) of a starter to use and sell in the next 3-4 years?  3) Do you want to build it once or plan to upgrade in the future? 4) What is your skill level and what tools and equipment do you have access to (can you weld, have a welder, know someone with a welder who welds AND will help you)?  How much $$$ can or will you put into the project?  5) How much time do you have?  

The reason I ask you to ask yourself is this will dictate what you do.  If this is a short term project the going cheap and functional is a good choice, if on the other hand, it is a long term project it might be better to "do it once and do it right".  Case in point, the rear end.  The folks who have posted have provided you with GREAT choices.  IF it's down and dirty an 8" is a great choice they should be easy to find and inexpensive.  If you are serious about an upgrade to a 5.0 of "hot" torky hi H.P. engine, I would opt for a 9" as it's REALLY strong and gears and parts are easy and "cheap".  

I grabbed a 9" out of an old '68 Ford wagon.  It is a couple of inches too long, but I was putting on rear flairs (3.5- 4") on each side so I could live with it.  If not it gets expensive it shorten the housing and axles.  You would be better off to bye one of the new sets then go this route.  You will also want to get a drive shaft and slip yoke for the rear end. (get the shaft from the same car if it's in a junk yard etc.) plan to have the shaft shortened and balanced.  

All of this assumes you have a good solid "rust free" car to start with! If not, you might want to address the body and "frame" first!

Hope this helps, good luck and keep asking questions!