This is the info for the idler pulley on 413 engines with air. The makings of a modern replacement for our idler pulleys are all readily available from your local Mopar dealer. This will fit all '59-'65 Chrysler & Imperials and other cars with 413 A/C set ups.

#3830196 Pulley ID
#9418275 Bolt Hex (Comes with attached washer for outside of pulley)
#0271502 Nut Hex
#5214065 Shield ID (Need 2 of these)

You will also need 1 or more 7/16" washers between inner shield and the support depending on your alignment and an optional lock washer behind the support and in front of the nut if you are the belt and suspender type.
The compression bolt & nut is hardened.
The bearing is sealed on both sides and made in Canada.
The pulley is made in USA.
Do not use the screw hex that is called for with the pulley. The bolt hex called for above is more substantial and comes from another assembly that uses the same bearing.
Do not order an after market pulley that replaces this Chrysler number because it will only fit a 3/8 in. belt. Our belts are 7/16 inch and this pulley accepts the 7/16 inch belt completely.
You will have to flatten one side of the bolt, where it passes through the support, so that it measures no less than .377 in. across the flat to the other side of the threads if your support still has the flat at 12 o'clock high. Use the existing bolt as a guide. The tighter the fit the better. If your support has already been drilled out round then this will not be necessary.
Retail list is $44.40 complete.