Rear end

[504DusterIR]

Hi how's everyone doing today?
I'm interested in upgrading my rear end, which way would be the easiest to upgrade to an cheapest? I don't mind doing modifications an what not , I have a 72 duster with a 5.9 Magnum swap an transmission is a 904, this would be all new to me ,I'm learning as I got

 

[Scody21]

What do you mean by upgrading? New gears or a new housing and gears? Post a photo of the diff housing you have currently…

 

[504DusterIR]

Couldn't get a really good photo

 

[504DusterIR]

I think it a 8 1/4

 

[YY1]

That looks like an 8 1/4 to me.

You'll probably be OK with that, strength wise.

 

[SIX225]

If someone swapped to an 8 1/4, I'd bet that the fronts swapped to discs and 5 on 4.5 too.

 

[Ricks70Duster340]

Hi how's everyone doing today?
I'm interested in upgrading my rear end, which way would be the easiest to upgrade to an cheapest? I don't mind doing modifications an what not , I have a 72 duster with a 5.9 Magnum swap an transmission is a 904, this would be all new to me ,I'm learning as I got

View attachment 1716247196

Why do you want to upgrade the rear? Different gears, current rear worn out? If your current rear is in good shape you might want to upgrade your torque converter instead.

 

[504DusterIR]

If someone swapped to an 8 1/4, I'd bet that the fronts swapped to discs and 5 on 4.5 too.

You are correct sir

 

[504DusterIR]

Why do you want to upgrade the rear? Different gears, current rear worn out? If your current rear is in good shape you might want to upgrade your torque converter instead.

Different gears possibly, might be the TC , I just feel like the duster isn't moving as quick as I think it should be ,feels like it takes a little bit to get going from a stop , it's not no means a racecar it's a daily driver

 

[Ricks70Duster340]

Different gears possibly, might be the TC , I just feel like the duster isn't moving as quick as I think it should be ,feels like it takes a little bit to get going from a stop , it's not no means a racecar it's a daily driver

TC's today are not what they used to be. The need to get the car moving better is exactly why you would use a better one on the street. Gearing is fine to change, but a quality TC will help immensely.

 

[Syleng1]

Sorry keyboard warriors- that looks 7-1/4” to me. Look at the tube diameter.
That is one hole shot away from the Big Bang theory.

Honestly we need more pictures-

 

[Scody21]

This should help with figuring out what’s in your car if it is original to the car. It is seeming like the 7.25..

 

[504DusterIR]

TC's today are not what they used to be. The need to get the car moving better is exactly why you would use a better one on the street. Gearing is fine to change, but a quality TC will help immensely.

Ok, I know that the transmission is from 1974 so I would guess it's the original TC

 

[504DusterIR]

Sorry keyboard warriors- that looks 7-1/4” to me. Look at the tube diameter.
That is one hole shot away from the Big Bang theory.

Honestly we need more pictures-

Ok I'll get more pics

 

[504DusterIR]

8 1/4 diffs have misc shaped covers, but always 10 bolts.

7 1/4 has 9 bolt cover.
8 1/4 has 10 bolt covers .
Cheers

I'll see if I can count the bolts

 

[504DusterIR]

I Got more pictures,

 

[504DusterIR]

Was told it was posi ,but Idk I spun the tires for research purposes only an it seemed like only the right side spun

 

[Scody21]

Was told it was posi ,but Idk I spun the tires for research purposes only an it seemed like only the right side spun

Yup, not a sure grip. That’s a one tire fire..

 

[504DusterIR]

Yup, not a sure grip. That’s a one tire fire..

Could I upgrade some part(s) to make it posi ? Or would that require a whole rear end? NICE DUSTER

 

[504DusterIR]

Could I upgrade some part(s) to make it posi ? Or would that require a whole rear end? NICE DUSTER

Maybe that's why it don't feel that quick ..One tire spin to get the car moving?

 

[stroked340]

What's done to the engine and transmission stock/modified??

 

[504DusterIR]

Stock 1974 904 transmission an 5.9 Magnum converted to a carburetor

 

[remytherat]

I would look for early dakotas and jeep xjs for gears and or a suregrip. Most have 3.55s, but you can also find 3.07, 3.21, 3.73, and 3.90

 

[504DusterIR]

I would look for early dakotas and jeep xjs for gears and or a suregrip. Most have 3.55s, but you can also find 3.07, 3.21, 3.73, and 3.90

Ok what modifications are needed to be done if any? I see on Marketplace around me 8.8 jeep xjs rear for sale

 

[504DusterIR]

Ok what modifications are needed to be done if any? I see on Marketplace around me 8.8 jeep xjs rear for sale

Don't think it was a 8.8 I think those are Ford