Swapping rearends, need your input.

[340 Dart]

You guys have been really helpful to me so far, and it it MUCH appreciated!!!

Here's another one for you.

I have a 74 duster with an 8 1/4 and a 904.
I have a 71 dart with an 7 1/4 and a 727. (po didn't finish)

I want to put the 7 1/4 in the duster. It has a 318 and will be a daily driver.

I want to put the 8 1/4 in the dart. It has a 340 and will be a Street/strip car.

Is this a direct swap?
Will I be having any driveshaft issues?
Is there anything I need to know before attempting this?

 

[grumpuscreature]

You may want to leave the Duster alone and consider an 8 3/4" for the Dart. What you want to do will work with some minor issues, but you are setting yourself up for a double rear swap down the road.

The Duster should have the 5 on 4 1/2" bolt spacing, while the Dart should be 5 on 4". You can get around this by swapping tires and wheels from car to car, but you will be left with the need for 2 spares for both cars or wheel adapters on the rear. The rears and attaching hardware are a direct swap from car to car, so the bolt in part is easy and straightforward. The only driveshaft problem will be length, if at all, and is easy and cheap to deal with. The 7 1/4" WILL fail behind a daily driver 318, it's just a matter of time. Broke more than one myself. The 8 1/4" WILL fail behind a street/strip 340. Ditto.

I am currently having an 8 3/4" housing and axles built for my 66 Valiant by liegel84.com and will wind up in the $600 range for the total rear from flange to flange with backing plates for 10" B/E body brakes. I got a screaming deal on the 3.23 chunk, but that's part of the fun. 8 3/4's are out there for a reasonable price if you know where to look. Hope this helps. :thumbup:

 

[dgc333]

The 7 1/4" WILL fail behind a daily driver 318, it's just a matter of time. Broke more than one myself. The 8 1/4" WILL fail behind a street/strip 340. Ditto.

You can break anything if you try but considering that millions of 318 A bodies were made and the stock rear end was a 7.25 and they held up fine in normal daily driving conditions. The 73 Swinger I picked up from a guy at work (he bought new) for the front disk brake parts had over 300,000 miles on it and the rear end never failed according to him.

Same for the 8.25, lots of A-bodies run low 12's and high 11's for years with an 8.25. It ultimately may not be as strong as an 8.75 but it is a stout rear end and is still being used under pick-ups and Jeeps.

Other than the bolt pattern and drive shaft issues mentioned the plane seems perfectly good to me.

 

[408duster]

If you cant easily and cheaply find an 8 3/4 unit for the 340, the 8 1/4 should last for awhile. Weve been using an 8 1/4 behind a 360 strip/street for some time. Both of the previous viewpoints have merit. Id recomend to put that 727 behind the 340 when you change things over..... the stock 904 would be marginal, but make the most out of what you have and the 904 would live a long life behind the daily driver 318.

 

[A/MP]

I have a Dana 44 w/4.56 Richmond gears a mini spool, a new uninstalled full spool and HD axles. This set up is narrowed and will fit in any A body. You can add your spring perches or ladder bar brackets. Brakes and drums and backing plates. Let me know if your interested.

 

[340 Dart]

I have a line on a 8 3/4 from 1000 miles away with the gearing I want. I just want to explore options and pick the best course for the car and the pocketbook.

The Duster should have the 5 on 4 1/2" bolt spacing, while the Dart should be 5 on 4".

I didn't even think of that! Thanks for pointing it out.

The goal for the 71 dart this year is low 12's. It will take me probably $400 to set it up with the duster rear and get a suregrip and gears.

I guess it would be better to just pony up the extra $300-400 and just get something I don't have to worry about.

Thanks for helping me decide.!

 

[19Challenger70]

Hello,
I have purchased an 8-3/4 housing from Liegel84.com to a custom width that i wanted for my 1970 challenger. I have also bought a complete Dana 60 from him and everything has come just the way i expected at a reasonable price. Maybe consider checking him out as he seems to really know his stuff and can give you his honest opinion as what he would do.

 

[res1vw21]

I can' remember did ma change the pinion angle between the dart (swinger) and duster? For some reason I have it in my head that they did.

 

[340 Dart]

Hello,
I have purchased an 8-3/4 housing from Liegel84.com to a custom width that i wanted for my 1970 challenger. I have also bought a complete Dana 60 from him and everything has come just the way i expected at a reasonable price. Maybe consider checking him out as he seems to really know his stuff and can give you his honest opinion as what he would do.

Thanks but the post is over a year old. I remember reading a year or two back into the archives when I joined. :cheers:

The 71 is long gone and the Duster now has a 8 1/4 suregrip with 4.10's.8)