What rear end do I have ?

[Doug Larsson]

I have a 1973 charger see 400 bb 2bbl auto. I was cleaning it to get the numbers off of it to see actually what I had. Does any one know to look up these numbers and tell. The only one I read if there's a 9 painted on it it's a 489 that's all I've found and read on.

 

[69Coronetrt]

The standard ratio would have been 2.71 with the 3.23 optional. Sure grip was optional with both ratios. http://www.hamtramck-historical.com...lershipDataBook/1973/73_Charger_Total0020.jpg

Assuming the rear end has not been changed:

If the car was built at the Lynch road plant (A in the VIN), then the axle assembly is listed on the tag. Post a picture of the tag and we can tell you exactly what came in the car when built.

If the car was built at the St. Louis plant (G in the VIN), then you will need to find the broadcast sheet to find the same axle assembly code. If you have the broadcast sheet, post a picture of that.

 

[Beekeeper]

let us see a pic of the back of the differential

 

[terzmo]

yes...picture the back

 

[69Coronetrt]

If it's a 489 case, we know it's an 8.75 axle. What we cannot tell by a picture of the back is what gears came with the car.

 

[terzmo]

If it's a 489 case, we know it's an 8.75 axle. Whate we cannot tell by a picture of the back is what gears came with the car.

if you know all that...spin the wheel and watch driveshaft rotation...one full rotation of the driveshaft...count how many times the rear wheel revolves....divide by 2 if non suregrip

 

[Car Nut]

 

[Beekeeper]

If it's a 489 case, we know it's an 8.75 axle. Whate we cannot tell by a picture of the back is what gears came with the car.

The question was what rear?

 

[Chargerjase]

73 Charger 400 2bbl will almost certainly be an 8.25 from factory. As mentioned before, the broadcast sheet will give all the info, or a picture.

 

[terzmo]

He wants to know what gears...said it's a 489 case...8 3/4

 

[Beekeeper]

He wants to know what gears...said it's a 489 case...8 3/4

Read again

 

[69Coronetrt]

IF it's a 489 case, then it's an 8.75 rear end.
IF he wanted to know what rear end he had, then the question was answered.
IF he wants to know what gears he has, then a picture of the rear is useless.

 

[Doug Larsson]

Here you go yes I think your right is a 8 1/4.

 

[69Bee]

8.25" rear end, and if you remove the cover, the gear ratio is usually stamped into the outside edge of the ring gear. It will be the pinion teeth and ring teeth, then you do the math.

 

[Doug Larsson]

I just had a new gasket put on in CA when I purchased the car. I'm not going to take it off at this time.

 

[69Bee]

Then, push the car forward (or backward) one revolution of the rear wheels, and count how many revolutions the driveshaft makes. You can get pretty close this way.

 

[Doug Larsson]

So two ?'s then can you put a sure grip in a 8 1/4 and if not what can you use off of the 8 1/4 if you purchase a 8 3/4 ?

 

[69clone]

So two ?'s then can you put a sure grip in a 8 1/4 and if not what can you use off of the 8 1/4 if you purchase a 8 3/4 ?

You can purchase a suregrip for an 81/4, but if you plan on building that 400 you may want to go with a 8 3/4, its stronger (8 1/4 won't handle much power) and the parts cost about the same. Unless you wanna go digging at a junk yard for 8 1/4 equipped Dakota and yank the sure grip out. The only parts off the 8 1/4 that could be used on a 8 3/4 I believe are the drums. I don't think anything internal will interchange.

 

[Doug Larsson]

You can purchase a suregrip for an 81/4, but if you plan on building that 400 you may want to go with a 8 3/4, its stronger (8 1/4 won't handle much power) and the parts cost about the same. Unless you wanna go digging at a junk yard for 8 1/4 equipped Dakota and yank the sure grip out. The only parts off the 8 1/4 that could be used on a 8 3/4 I believe are the drums. I don't think anything internal will interchange.

So doing one legged burn outs isn't a good idea huh lol.

You can purchase a suregrip for an 81/4, but if you plan on building that 400 you may want to go with a 8 3/4, its stronger (8 1/4 won't handle much power) and the parts cost about the same. Unless you wanna go digging at a junk yard for 8 1/4 equipped Dakota and yank the sure grip out. The only parts off the 8 1/4 that could be used on a 8 3/4 I believe are the drums. I don't think anything internal will interchange.

So I guess I should quit doing this huh until I get a 8 3/4 ha ha.

 

[69clone]

So doing one legged burn outs isn't a good idea huh lol.

So I guess I should quit doing this huh until I get a 8 3/4 ha ha.

haha I did them too. Always looked funny seeing out one burn out mark when you drove back around. I don't wanna tell you wrong but I don't think you can really do any harm unless you had a suregrip and stickier tires. I mean those A body guys do burn outs with them but they're lighter.