have questions on rear end on my 70 challenger

[stang13]

Hi
I am in the process of swapping out my 323 gears fir 370's and have a couple questions . I have a 70 challenger with a 440 six pack and a 727 torque flight trans . I do know that the rear is a sure grip / Posi with factory 323 gears . To order the gears I need to know what type of rear it is Dana 60  , etc ? How can I tell ?

Also will I need to change outr the entire center section or only the gears ?

Thanks
Tom

[stang13]

Here is  a pic of the rear if this helps , the car is now assembled

[moparman82]

That's a chrysler 8 3/4, you can grab a center chunk  with the gear ratio you want or just order the gears.  But u will need to know which housing you have.  Look for 489 or 742

[stang13]

where would the 489 or 741 be marked on the rear  ?

[moparman82]

Should be stamped on the center housing

[Chryco Psycho]

Cast on the side where the pinion runs , could be 4 different # 741 , 742 , 489 & one other

[joelson6]

hey, i have 3.73's in the 8 3/4 that's in my '74 challenger. i really like them for the street. with a 28" tire, 65 mph is around 3000 rpm. i have a 4 speed so you might be slightly higher with the 727.

[stang13]

  excellent !

Thanks everyone !!


Tom