Correct Rear Axle?

[1970GTX]

Hi all,
My '70 GTX has a 8 3/4 diff with 742 casting. Is this correct or has it been replaced at some point. Everything I read is that the 742 castings were phased out in '69 and '70s should have a 489 case. Build date is Feb. 1970.

 

[RustyRatRod]

In all liklihood, it's the right one. I have a 65 Coronet that has the old style tapered axle rear end in it. It appears to be original. Probably a leftover.

 

[Budnicks]

Most 70's performance cars with an 8-3/4" rear axle housing had a 489 carrier, 69 was the year of the big change from the 68 & earlier 742 carrier to the 489, probably some overlaps in late 68 & early 69, there's nothing wrong with a 742 carriers, they are plenty damn strong, it's just not 100% original correct for a 1970, but acceptable non the less, to most concerned Mopar Gurus & unless you going for a 100pt total #'s matching, full OEM restoration, it just fine....

- - - Updated - - -

but Chrysler did some strange stuff back in them days, the housing could be a 70 build date & the carrier could be an earlier unit...

 

[1970GTX]

Yup, Lynch Rd. car for Canadian export so who knows. It's a #s car otherwise, (engine, trans., rad support, and trunk lip etc. ) Fender tag and build sheet both say 8 3/4 3.55, but it has been changed to a 3.91 ratio at some point but I'm going back to the 3.55.

 

[Meep-Meep]

I believe what Budnicks says is true, at least based on what I have seen over the years.

 

[65 Plymouth Satellite 426]

Whatever Parts Were Left Over On The Assembly Line At The End Of The Model Year Got Shoved Into The Last Vehicles Coming Down The Line! Kinda Like The 62 Polara 4 Door With The 413 Max Wedge In It! Chrsyler Said It Never Existed! Lives Here In Pennsylvania! Boy Were They Ever Scrambling When Being Told It Did Exist!