What axle do I have?

[RamblinMan69]

I found an 8 3/4 axle supposedly from a Challenger. It has 207074 stamped on the housing. It is posi trac cause when u turn the u joint both axles turn same direction.  I've seen there are several variations some more desirable than others. I want to put it into my 69 charger 440 which currently has an open axle. I read somewhere a 741 is the weakest and the 489 is the strongest?

[Dino]

You're missing a digit there, should be 2070741 so yes the weakest of the 3.  Don't let that scare you though, it's still a very strong axle.  The sure grips (posi is for those other guys) came in clutch or cone design and I have no clue which you have.  One is always preferable over the other but my knowledge on these is very limited.

Unless you go racing with sticky tires, either version should be fine on the street.

[RamblinMan69]

Thanks for the info! I looked back twice at that stamping number and never saw the 1 at the end. Above that stamping there was another number - 253 and 10. Don't know what they mean, if anything?

[Dino]

You're welcome.  Unfortunately I do not know the meaning of the other numbers, but some people here will know I'm sure.   

[moparnation74]

741 - small stem pinion 1-3/8"  Casting 2070741 1964-1972, Sure grips were installed in some of them.

742 - large stem pinion 1-3/4"

489 - tapered stem pinion 1-7/8

You will not experience any problems with the 741 case for street use.

[John_Kunkel]

I read somewhere a 741 is the weakest and the 489 is the strongest?

Just because the 489 has the largest stem doesn't mean it's the "strongest". The 742 has the largest rear pinion bearing and many believe that makes the 742 the strongest.

In many cases where the last digit is missing from the main casting number you'll find that digit larger and higher up on the housing.......look for a single large 2.

[RamblinMan69]

Thanks for all the info guys! BTW, is it best to swap the "chunks" out or can I swap the entire assembly. I think I will need to change the brackets maybe?

[Dino]

Thanks for all the info guys! BTW, is it best to swap the "chunks" out or can I swap the entire assembly. I think I will need to change the brackets maybe?

The e body axle will not fit a  b body without modifications, I'd simply swap the chunk and be done with it.  Super easy with a good jack and some stands.  Use some black rtv around the gasket or in place of.