frdnut

I have worked on probably half a dozen mustang IIs including a king cobra and non of them had track locs..
The 8 inch is just weaker than a 9 inch due to its smaller design...Blowing the caps off the back of the carrier or breaking the pinion out of the front seem to be the biggest issues so I can't see how a different carrier would make it stronger than even an average 9 inch.......That's not to say the 8 inch rear is no good...I have one in my 68 that has stood up to many years of pounding with a 300hp 302 and a 4 speed...

2+2GT

All 1968-2011 Traction-Lok differentials work on the same principle, using axle-gear thrust to increase the clutch pack pressure. GM has used this same principle since the 50's, in their Positraction differential.

MonsterBilly

i did a 8.8 out of a 2000 exploder. total $ out of pocket was about $250. it did take a lot of labor though.
i have a pretty well worked over 289. i dont know the hp of it but i am assuming about 275rwhp. I am running a T5 out of a 1990 cobra.
It made a huge difference. The rear end cam with trac loc and rear disc breaks as well as the 3.83 gears.
results: it preforms great. I hammer the shat out of it constantly and have no issues. i drive it every other day for long freeway cruises and it is fun. I do think that the gearing could be a little lower though. 4.11 would have been perfect with the overdrive that it has.

I did this because it was cheap. if i had more funds i would have gone a different route. there is a guy on ebay that sells a 8" 3rd member with trac loc and whatever gear you like for about $700 + shipping. that is the best price that i have seen on an 8" option.

If you look you can find a 9" rebuilt with new stuff to match your car for around $1100 commonly on craigslist but then you will need to figure out shipping and hope that it is what it says.

Wjich ever way you go you will notice huge results. the locking diff and gears make more of a performance channge than just about any engine upgrade.

67mustang302

I've been running over 300rwhp through my 8" for years, over 225k on the engine and rear, never had an issue. Running a Detroit Tru-Trac now, had a Richmond Powertrax but didn't like it(auto locker unit). The Tru-Trac works like a posi type unit, but without cluchtes etc to wear out, so far more reliable and a lot stronger.

8" are actually really good rear ends, but they get looked down upon because it's a "smaller" 9" and therefore seen as weak. While it is weakER than a 9" they're still pretty strong. I've seen people blow up 8.8 and 9" rear ends with less power than I have in my 8. It's mostly in how the rear is set up and how it's driven. I personally wouldn't trust my 8" on drag radials with 4k rpm launches, but on street tires for a road race setup it's far more than adequate.

If you're really concerned, Currie sells an aftermarket aluminum 8" housing that's stronger than the stock ones. But at that point it may be cheaper to go to an 8.8 or 9.

http://www.currieenterprises.com/ces...E.aspx?id=2435

mr_velocity

Everyone keeps talking HP breaking the rear, torque will break the rear if you can get the tires to hook up. Post some torque numbers, depending on how noreins builds the 351 its going to make more torque than a 289.

2+2GT

True- My 289HP/4-speed is driving a 9" 4-pinion 28-spline Traction-Loc, but the final application is via a pair of 205/70R14 radials. I probably don't need to worry about the diff.

jspagna1

I've had my 8" in my car with 3.55's for the last 14 years and so far so good. Although I don't drag race the car and it's an Auto. See sig below for mods.

nba1341

I have an Auburn with 3:80 gears and a c4. Not fun driving on the highway but the farthest one way I have ever gone is 30 miles.

NoReins

Ok, thanks for all the input. Maybe I should throw a couple things out here. First, those numbers I said, 350-375 were ballpark flywheel numbers I wanted to aim for for the motor. I am not looking to have the biggest ***** on the street (don't forget, I'm a girl and I don't have them hehe) because in reality I'm sure I will baby the snot out of the car anyways. The suggestions of going with the 9 inch are appreciated, but with as mild as a build we were contemplating, we thought it wouldn't be necessary. Trust me I'd love to say we were putting in a 427, 9 inch yada yada, but really I can't see it ever going down the track. Does this change anything?? I am considering everyone's comments but the bottom line is, I don't want to buy a 9 inch if I don't need to.

2+2GT

I doubt you'll need a 9" for your intended use. As for the other, is that you in the icon?