741 to 742 swap

[Dreamcar]

Hi. If I want to change to from a 741 to a 742 diff, can I just swap the cases or do I need to get the entire rear axle assembly? It appears to be easier to get gears/parts for the 742, but I've got a complete 741 rear axle. I plan on having everything rebuilt anyway.

Having to ship or transporting just a case is much easier than the entire rear axle. 

[John_Kunkel]

What year? If it's '64 or later you can remove the 741 3rd member and replace it with a 742 3rd member....if it's '63 or earlier the same swap could require an axle shaft change.

[Dreamcar]

Its a 69 so that's great news. Thanks

[Dino]

The u-joint may be a different size though so measure before install in case you need to go buy one. 

[Dreamcar]

The u-joint may be a different size though so measure before install in case you need to go buy one. 

Good to know. Thanks!

[flyinlow]

742's Suregrips have a button in the bottom of the axle well that the two axles press against to set the end play.  Make sure the carrier still has that  unless you are going to run "green bearing" on your axles.

[Dreamcar]

742's Suregrips have a button in the bottom of the axle well that the two axles press against to set the end play.  Make sure the carrier still has that  unless you are going to run "green bearing" on your axles.

You've lost me since I know very little about axles...all I know is that I'm buying a 742 case (found a non-sure grip with 2.76) that I was planning on having rebuilt with 3.55 gears and limited slip...Are you saying that I may not be able to?

[flyinlow]

No it will work. If the 742 was a factory suregrip there are two buttons that the SG unit uses. I got one once and they where missing. can't set the end play without them.If you are going to have it rebuilt and the limited slip unit added ,they will take care of that for you.

[flyinlow]

These are the buttons

[Dreamcar]

No it will work. If the 742 was a factory suregrip there are two buttons that the SG unit uses. I got one once and they where missing. can't set the end play without them.If you are going to have it rebuilt and the limited slip unit added ,they will take care of that for you.

Perfect! Thanks

[Cooter]

Also, ill add that even with big joint on shaft, small joint on chunk and vise versa, you can purchase what is called a combination joint round here to make it all work...big on one side and small on other. I used to have the number but can't find it now..

[Dreamcar]

Also, ill add that even with big joint on shaft, small joint on chunk and vise versa, you can purchase what is called a combination joint round here to make it all work...big on one side and small on other. I used to have the number but can't find it now..

More great info. Thanks