Patrick Dykes sells an A/C kit from
Old Air Products. Both sites are a little vague about what type of crank pulley to use, other that a 3/8" belt is to be used.
Buffalo Enterprises makes a dual-groove crank pulley-dampener for a 216-235-261 from a 292 pulley. I have one on my street rod with a 261. Steve at Buffalo does not have a website. You will need to call or write him:
25625 Dahl Road, Arlington, WA, 98223
(360) 652-7684
However, I do not have an A/C system on a 235-261 (yet), as I am between Stovebolt trucks.
Hoyt