1973 Challenger Rear End

[Fordication]

What case and rearend would a 1973 Challenger with a 318 come with. 489?

 

[Chryco Psycho]

Yes

 

[pschlosser]

maybe a 7.25 (the smaller) rear end.

 

[Vaanth]

What case and rearend would a 1973 Challenger with a 318 come with. 489?

The 1973 Challenger was only available with the 8-3/4" rear axle. The only 8-3/4" axle center section in 1973 was the 2881489 housing, aka "489", with a 1-7/8" pinion.

The standard gear ratio for the 1973 Challenger was as follows:

• 318 or 340 with 3-speed manual transmission: 3.23:1
• 340 with 4-speed manual transmission: 3.23:1
• 318 with automatic transmission: 2.76:1
• 340 with automatic transmission: 3.23:1

The optional gear ratio and/or Sure Grip for the 1973 Challenger was as follows:

• 318 with 3-speed manual transmission: 3.23:1 Sure Grip
• 340 with 3-speed manual transmission: 3.23:1 or 3.55:1 Sure Grip
• 340 with 4-speed manual transmission: 3.23:1 Sure Grip or 3.55:1 Sure Grip (with A36 package)
• 318 with automatic transmission: 3.23:1
• 340 with automatic transmission: 3.23:1 Sure Grip or 3.55:1 Sure Grip (with A36 package)

The A36 Performance Axle Package included the 3.55:1 ratio gear set with Sure Grip, plus a 26" Mx Cooling radiator with shroud and power steering oil cooler (if equipped with power steering).

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[moparleo]

Remember that when it comes to original parts on Mopars, the books are not always 100% accurate.
My last 73 Challenger was one owner, original running car .
My 318, 73 Challenger came with a 741 pig.
If you can find a good 742, it is plenty strong an easier to set up than a .489. Much less expensive too.