How to indentify rear and gear?

[99ss]

As stated how do I indentify rear and gear set ?

 

[Deleted member 214]

Easy way to check for gear set, look for a tag on the housing. If none, put rear up on jacks, put the car in neutral. Get under the car and have somebody watching the back tires. Rotate the driveshaft. If the wheel goes around 3 and a half times for every time the driveshaft goes around once, you have a 3.55 gear. 3 and a quarter times, you have a 3.23.

If the back side of the axle housing is solid and there are bolts on the piece the driveshaft connects to, you have an 8 3/4 rear. Other rear ends have a cover on the back side.
Identified by casting number & number of cover bolts. The 8.75 (8 3/4) rear end LOADS FROM THE FRONT and IS THE ONLY REAR END THAT DOESN'T HAVE A REAR COVER.


Casting# Year Body Size Notes

2070051 1960 - 71 A 7.25 9 bolt cover
2070062 1970 - 71 A 7.25
3507881 1972 - 74 A 7.25
2852905 1969 - 70 B 8.25 10 bolt cover
3723598 1971 - 74 B 8.25
3723599 1971 - 74 B 8.25
1634985 1957 - 67 ABCD 8.75 10 studs/no rear cover
1820657 1958 - 64 C 8.75
2070741 1964 - 74 ABCE 8.75
2070742 1959 - 68 BCD 8.75
2881489 1969 - 74 ABCE 8.75
3507890 1973 - 74 B 9.25 12 bolt cover
3507891 1973 - 74 B 9.25
Dana 60 1966 - 72 B 9.75 10 bolt cover
Dana 60 1970 - 71 E 9.75

This should get you started.

 

[detmatt1]

Nice work Greggs70! All that I'll add is, if you end up with the back tires off the ground with a buddy put a mark on the inside of the rotating tire at 6 oclock with chalk or a piece of tape (and you know what it means when only one is turning). This will make it easier to keep track of how many rotations.

 

[FridayGt]

Here's a thread that I posted on this topic about a month or so ago. In it, Cranky posted a really great picture that can aid you in identifying at least the size just by looking. Hope it helps.

http://www.forbbodiesonly.com/moparforum/showthread.php?t=24409

 

[99ss]

Thx guys, I found that picture in a search as well, thank you.. appreciate the help

 

[64Belvedere]

Don't you rotate the tire once and count the driveshaft revs? a 3.23:1 would turn 3.2 times for every one turn of the tire and a 3.91 would be almost 4 driveshaft revs hence the steeper gear and the higher RPM. Been a while but I think that's how I always did it.

 

[Cranky]

Don't you rotate the tire once and count the driveshaft revs? a 3.23:1 would turn 3.2 times for every one turn of the tire and a 3.91 would be almost 4 driveshaft revs hence the steeper gear and the higher RPM. Been a while but I think that's how I always did it.

Yup...so long as it's a limited slip (SureGrip) rear, it works that way.

 

[Ron 73]

Yup...so long as it's a limited slip (SureGrip) rear, it works that way.

There is a different way on a non-suregrip?

 

[bigmanjbmopar]

There is a different way on a non-suregrip?

It's not as accurate as the posi with this method, one legers need to be spun about 10 tire turns then count the yoke revs and I think an average or something is what you use, at least that's what I was told.

on my posi aka surgrip I used a ty-rap on the drive shaft pointed the end up and used blue tape on the tire. Got 3:55's in a 8-3/4. I had no tag so between the casting numbers on the center section and the tire spin method I found the gears, Also test drive 60 mph at 2200 rpm 70 mph 2600 rpm.

If you have your center section out the gear ratio is marked on the gear set I believe.