Sometimes you just need a part that works, like a choke cable.
Check out some of these vendors that have a great selection of stock parts for your tractor, old or new.
Yesterday's Tractors - new and NOS parts, also classified ads.
Steiner Tractor - new and NOS parts.
Jensales - new and NOS parts.
SSB Stractors - new and NOS parts.
TractorHouse - auction site for whole tractors.
Equipment Trader - auction site for while tractors and other equipment.
The Old Tractor Company - limited supply of new and NOS parts.
Wengers of Meyerstown - new and used parts.
Tractoropolis - new and used parts.
eBay (obviously) - new and used parts.
CaseIH parts store has a surprising amount of information, including a lot of construction equipment.
Farmall Cub Forever - specializing in Farmall Cub parts.