What Alternator do i need??

[Onewickedchallenger]

I am putting back my 70 Challenger 528 Hemi. When I bought it It did not come with a alternator. Looking to buy a one wire alternator. I see they make two. One that is called "square back" the other i do not know what it is called, anyway i am using the OEM mounting brackets. Which one do i buy?

Thanks

[4 speed fish]

THe round back is the correct one.

[Topcat]

[Topcat]

Some additional info:
For a 71 model year car (built from 08-70 until 06-71) you should have a "round back" alternator. For a hemi application it should be either a 3438176 (37 amp) or a 3438177 (50 amp). The pulley on that alternator should have the part number 2095059 stamped into the hub face. The assembly date is what your looking for as far as date code (DC) and it should be a three or four digit numeral stamped into the alternator directly above the output stud. Usually the alternator DC will predate your cars SPD by a couple of weeks to 6 months prior. It is not necessarily related to the engine DCing.

[Onewickedchallenger]

Thanks Great info.

[MEK-Dangerfield]

That's interesting as my alternator is a square back. Of course my car isn't exactly stock either.   

[brads70]

Saved that picture, thanks Topcat! I always wondered were the green and blue wires went of if it mattered if they got mixed up!

[mint6551]

I am putting an alternator on a 440 that im putting in my 1973 challenger, just was wondering what the difference is between round back and square back? 440 source only sells square backs for a 440

[Chryco Psycho]

Both work the same , round back were used in the 60s using a switched power  , up to 70 the first year  they went to ground switched field ,

[anlauto]

Both work the same , round back were used in the 60s using a switched power  , up to 70 the first year  they went to ground switched field , in 71 they went to larger square back 

Really ?

[Chryco Psycho]

corrected it , either my memory is failing or I had the wrong info , I thought 70 was the last year for the round back , oddly I went into canadian tire & ordered an Alt for a 70 & got a round back not the usual square most rebuilders give you