http://www.jalopyjournal.com/forum/...ring-pinion-gears.1015591/#post-11476035

Strongly consider buying an installation kit:
http://www.classicparts.com/1955-62...omplete/productinfo/93-514/#.VxjpKhMrKdE
http://www.classicparts.com/1955-62...ite-Kit/productinfo/93-515/#.VxjpOxMrKdE

Maybe some who has done the 3.38 swap will post about their experience.

Many people have done the 4.11/3.90 to 3.55 swap in earlier trucks.