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Discussion Starter #1
67 Coupe
289 v8
4bbl

I've been told my 7 1/4 differential is too small for the my 289 and that I need to upgrade to an 8 or 9''. Very hard to find either of them, at least where I am, but I have found two possibilites and now come to a choice. There is a seller willing to trade a 9'' for $380. There is also an 8'' for $200. Still waiting on ratio info. I know the 9'' is stronger and better for raceing but I don't plan on putting anything larger than the 289 in the car for quite some time though I will be doing other things to improve it's performance. If I do decide to get a bigger engine later though it will probably be even harder to find a 9''.

Can anyone offer some wisdom to aid in my dilemma?
 

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Hello.:) Those prices sound about right for the third member only.That's just the center section with the actual gears in it.You will also need the axle housing, axles, etc... The entire assembly generally goes for over a grand for a 9 inch and not much less for an 8 inch. If that actually is the entire assembly, I'd buy them both, put one on my car and sell the other for what I paid for both of them.But that's just me.Hope that helps.:)
 

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I've never paid over $125.00 for used 9" or 8" center section in my life (and yes they all ran fine). You just need to do a little more shopping! You shouldn't have to pay more than $300.00 for a complete used axle.

For a 289 an 8" will be fine. Unless you're racing, don't worry about it being a posi. Without and overdrive transmission I wouldn't go lower than a 3.25 gear. Have had 4.11s and 3.50s in the past myself, for a basically stock motor with stock diamater tires, they're too much. Keep things in perspective, 3.25 with a C-4 or 4-speed will be your best.

Look for a good old fashion junk yard and take a tape measure for checking the axle width. 9" are more plentiful than 8" anymore. For 8" look under Mavericks, Pintos (yes Pintos used an 8", that's where my 3.25 posi came from) etc. Otherwise swap meets. If you live near Ohio, the big Ford swap meet (in March I think) will have lots to choose from.
 

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So, where are you at? 67/68 coupes are not all that hard to find. If your car has a 71/4 rear end it means it was probably a six cylinder car. If you haven't upgraded the suspention you may want to think about picking up a parts car and swapping what you need it would be cheaper in the long run. Don't run a V8 in a six if you haven't upgraded the whole suspention/brake system it's just not a safe thing to do. Coupes can still be had at reasonable prices and if you don't need body parts you should be able to pick up a rust bucket for a song. Your local want ads should have a couple and ebay occasionally has a parts car for sale.


Mike
 
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You don't actually need a parts car, nor would I suggest it. You can get the same parts brand new(which is probably safer, I personally wouldn't want to trust 30+ year old suspension and brake parts). Just buy the parts new, it's not all that expensive(I'm currently doing a 6 to 8 swap).

As far as the rear-end goes, I think everyone misinterpretted this gentleman(or maybe I did). It sounds to me like these are complete rear-ends, but perhaps they've got some miles on them(perhaps he found them in the classifieds or something). So depending on how old they are and the condition they're in, they may very well be worth the price. And an 8" is all you're going to need. You gotta also remember, that if you don't actually need the strength that the 9" provides, then you're actually killing some of the performance from your car, because a 9" weighs significantly more than an 8".

And everything is relative man. It all depends on how old the rear-end is, what condition it's in, what exactly it has in it(if it's a high-demand gear and/or posi, they're obviously gonna want more for it). I myself bought my 8" from a buddy of mine for $100 COMPLETE. It was a non-posi unit and had like a 3.00 gear if I remember correctly. It was a steal(I think I got a bit of a price break since he was my friend), but I also got it so cheap because it needed rebuilt definitely. So I had it rebuild, with a clutch posi unit and a 3.80 gear! Now you don't have to go to that extreme, but that was just for my application.

Ya see what I'm sayin though, rear-ends are relative. You can read all these replies, and everyone's prices and things are different. Simply because we all live in different parts of the country, some places where parts or more readily available than other parts of the country. So just take the knowledge that you're likely gonna want an 8" rear-end, and just be wise with your decision. Consider the condition, wear, age, etc. when looking at rear-ends and their prices.

Whew, sorry bout that long reply. :sleeping:
 
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