Help with part number (pulley belt)

[skid440]

Hi,

The belt in the picture is what the folks say fits my 70 challenger 440 with the smaller diameter inner crank pulley.  I have a single pulley alternator that aligns with the crank pulley.  This belt shown is way too big.  Can someone shoot me the correct belt pulley for this combo??  Thanks  John 

[Chryco Psycho]

you will probably have to do a trial & error , I would take a piece of string & measure the distance around the pulleys & get a belt with a slightly longer measurement