I have a 74 Duster with a 225/904 with a fresh 7 1/4 rear. The transmission makes a moaning noise in first gear but quits as soon as it changes gears. It shifts very good and doesn't slip any. Here is a tip, the guy who had it before me pulled a boat with it which screwed up the 8 1/4 it had in it when I got it. One more thing, are these 7 1/4 rears as fragile as most people say they are?

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

All you can do is drop the trans pan and take a look for signs of trouble in the form of crap in the bottom of the pan. (a pro trans rebuilder can "read" the flakes in the pan like tea leaves and predict the furture of you gearbox!)

Change the filter and fluid, crank-up the main line pressure a couple of turns and see if she still makes the noise.
DD

I dropped the pan and changed the fluid & filter when I got it home. Everything looked fine, no metal in the pan or filter. The only thing that bothered me was that the fluid had a really burnt smell and was solid black instead of the usual. Now how about the lifespan of that 7 1/4?

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

The spirits say, 'it's a toss-up which one dies first.' That really burnt smell does not bode well. Yes, the 7 1/4 is that bad.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

So my bone stock slant can break the 7 1/4. Man these things suck. At least I have an 8 1/4 A-body rear under my 75 parts car. All it needs is a new ring gear.

Whay would chrysler use something so sh@#*y as the 7 1/4 any way?

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

they did it to save money in a failing buisiness...Then they led the way in gas saving vehicles such as the K car...Led the way in front wheel drive.....The govt. said every vehicle produced must average a certain mpg... Chrysler complied: and when FORD failed; The govt. let them slide!!! I'm trying to tell the TRUTH !!!!!! MOPAR RULES !!!!

I just ran a 18.96 with an origional stock 7 1/4 rear. 20 years and at least 75,000 miles have yet to break it.(normal driving)

If you push them hard, eventually you will wear out the "spider" gears (I think that's the correct term). A sure grip unit protects the spiders, and will therefore prolong the life of a 7 1/4 even under heavy use.

There is notable weight difference, so may consider looking for a sure grip or just running it till it dies. There might also be a place to get stronger spider gears.

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1980 Aspen 225 super six

This thing is geared up too high to be concerned about weight saving. The 8 1/4 it used to have under it had 3.92 gears in it. Even though it could only run 70 due to the gearing, I had a lot of fun with it until the ring gear started screaming. Add 3.92s to your bone stock slant. I bounced a lot of Ricers with this thing.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2