9 inch ford?

[Lightspeed]

ive got a 67 mustang and i was thinkin about puttin a new set of gears in it but then i was informed that some years of broncos had 3.73s in them and that i could probly get a 9 inch bronco rear end cheaper than buying the gears and having someone put them in...does anyone know what year bronco this is? if it will work at all? or a better alternative to my problem...id like to be able to keep the same length rear end or maybe a tiny bit shorter and the same bolt circle if possible thanks for any imput

[gofastmercury]

It would be easier to just put in the center carrier. It changes out very easy. To find out the gear ratio out the donor bronco, there should be a tag on the diff saying the ratio. Alot of broncos had 3.50's but I'm sure finding a 3.73 won't be too hard. Good luck.

[mustangII460]

Like gofast said, change center sections.

*note* make sure if you get a center section it has a drain/fill plug. Early type 9 inch had them in the housing. Count the splines too.

[Shaggy]

Are you sure you want 3.73's with a c-4 if you are not running real tall tires you won't be able to finish the 1/4 in your power.

My set up is shifting at 6 i have 3.25's with 24" tires and i am just about done at the end of the 1/4. I would like to go to 3.50's because i could run a 26" tall tire and be at the roughly the same rpm atr the finish line

ps my freeway cruising with my loose convertor has me spinning between 3500 and 4000 if i had to spin any higher than that i would go ape $h1t it already drives me nuts as it is.

[Lightspeed]

forgot to mention this car has an 8 inch rear end in it now and will not be run in the 1/4 because i only have an 1/8th mile track near where i live and will probly never see the interstate unless of an emergency taking this in to consideration maybe it will help out a little

[gofastmercury]

Well, the eight changes everthing.
A nine center will not bolt up your housing, A bronco diff, as far as I know, will not "just bolt in." On the other hand trac locks are not that easy to find for the eights. Do you have one now? If you do, then it would be easier to just change gears. If you have tools and you most of your work at home allready, setting up the ford diffs aren't that hard, and the gears themselfs are not a lot of money. I did my first one after reading a article in hodrod. It lasted till I tried to put 400hp though it. That was an eight too.

Since factory nine's are a little hard to find for comets, I took a nine out of a truck, cut the ends off my eight, after measuring everthing carefully. Cut the ends off the nine, since I have a wheel align rack at work I set it up, made it all zeros, and welded it up!
Its been in the car for about a year and a half, no probs.
Not for the feint of heart, but it saved me about a grand.

Kind of a long answer, isn't it?

[Lightspeed]

well some of the info was helpful...i do appreciate it...its not a posi lock rear end tho and so i guess i can just do without...id like to put a set of 3.55s or 3.73s in it even tho i think the only set above a 3.55 is a 3.80 on a ford 8 inch rear...im probly just gonna have 375 horses tops so i figure thatll be probly good enough to hold it all together

[mustangII460]

I put a 68 9inch in my II. Luck had it, it bolted up. Then I tubbed it, back halfed it, front halfed it, 10 pt caged it, then sold it.

At first I still ran the stock 68 wheel with 29x9 slicks, they didn't scrub.

[hobgoblin351]

The bronce switch sound good, since it already comes with the posi. But dont forget about the mid 80's Lincoln Versailles. Thats a straight bolt in too, and it comes with DISC BRAKES!! I dont think it comes with a posi though. But an upgrade kit for disc brakes is alot more expensive than a limited slip for the 9-inch. Just something to think about. goodluck