Stock Rear End Size and Gear Ration in 71 Demon 340

[Gibber]

Hi,

Trying to find out what stock rear end size and gear ratio was fitted in 71 Demon 340 with 4 speed.

Thanks in advance,

Mark

 

[Dana67Dart]

I would assume an 8 3/4

As for gear ratio. Look in yoyr factory service manual so e times they list what was stock for a particular application

Do you have a fender tag or a build sheet?

There are options that could have been ordered for gear ratio, like a towing package might have a diferent ratio, a limited slip might have another ratio

 

[33IMP]

71 340 car would have an 8 3/4.
As for gear ratio, i would bet on a 3.23 open being the base gear, with 3.55 and 3.91 optional, along with suregrip.
Happy to be corrected by somebody that knows for sure.
Easy enough to find out what you have. You'd need a couple pieces of tape, and a floorjack (and jack stands!).

 

[dadsbee]

 

[Gibber]

Thanks much! It will be going to a friends shop to use his lift for pics of the NOM engine and transmission VIN numbers. I'm planning on offering it for sale in the next month or so. I have the fender tag but haven't looked for the build sheet yet.

Mark

 

[Sublime one]

Hi,

Trying to find out what stock rear end size and gear ratio was fitted in 71 Demon 340 with 4 speed.

Thanks in advance,

Mark

Mine is 8 3/4 with 355

 

[Dana67Dart]

Fender tag might tell you what it is.

 

[MopaR&D]

If you can't figure out from fender tag or build sheet you could just jack up the rear of the car and spin the wheels, see if both wheels turn the same direction (if yes, you have Sure-Grip) and also count how many times the driveshaft turns with one full rotation of the rear wheels. IIRC 4-speed cars usually came with 3.55 or numerically higher gears, starting ratio with 3.23s is kinda tall with a non-OD A-883.

 

[YY1]

Dealer data books at hamtramckhistorical should show what the standard and optional rears were depending on other options and packages.

 

[33IMP]

Agree with mopar r&d. I f were your buyer, i wouldnt give a crap what "stock" is, i would want to know whats in it now.
Factory info about what might have been in it 50 years ago doesnt mean as much as whats in it now.

 

[33IMP]

If i buy a car that the fender tag or broadcast says came with a 3.91 sure grip, and i find out its got a 3.23 open, im gonna be pissed.
You better find out what is there, rather than depend on what was stock 50 years ago.

 

[71GSSDemon]

Mine is an auto car, but came with 8.75 and 3.91 SG

 

[Gibber]

I’ll find out what’s in in before I list it, thanks.