1966 300 383 w/ 3 Speed Auotmatic

[Justin Heydon]

Hello All,

Having a tough time locating the casting number for my rear differential. Anyone know if mine would be 741 or 742?

 

[stubs300]

IDK? You'd have to crawl under there and look to know for sure. Why you asking? Good Luck

 

[Justin Heydon]

Need to replace the input shaft seal. Two different numbers on RockAuto.

 

[stubs300]

Need to replace the input shaft seal. Two different numbers on RockAuto.

Like I said, crawling under and getting the number first hand, by yourself will give you the most correct answer! Then you won't have to say that someone here gave you bad intel. Why is this so hard for you understand?

 

[gyknot]

It will be on the forward part of the carrier on the drivers side of the car. Probably will have to scrape off a bunch of hardened on grease and dirt but it will be there in fairly large cast numbers.

 

[Big_John]

To illustrate where to look:

Replacement with a later model, like this 489, is not unusual, so you really need to verify.

 

[CBODY67]

When you find it, for general principles and such, you might get a picture of it on your phone for future reference.

CBODY67

 

[70bigblockdodge]

The 741, 489, and 9 1/4" all use the little seal, cheap one.
The 742 uses the big expensive seal.
The 489, and 9 1/4 both use crush sleeves and require a special procedure and tools.

 

[commando1]

9 1/4 use(s) crush sleeves and require(s) a special procedure and tools.

What "special tools"?

 

[70bigblockdodge]

What "special tools"?

Inch pound torque wrench that can measure the turning torque of the pinon nut prior to taking it off, (not a micrometer adjusted one ) so you can return it to the same value, for proper bearing preload. You can also just crank it back on and hope for the best. In that case, no special tools.

 

[commando1]

Inch pound torque wrench

That ain't "special". Every tool box should have one.

 

[70bigblockdodge]

That ain't "special". Every tool box should have one.

Noted!

 

[james bernard]

Pretty sure you’ll find it’s a 741. I think the 742 became more common in late 67 but I could be wrong About that