Diameter of the thread is 7/8" that is rare. From top of the thread to the shoulder of the outer tube is also 7/8". I don't know how to count the number of the thread(ridge) per one inch length but please refer to the picture attached. Two of the legs have a ring attached to the inner tube which probably serves as a guide to attach the pedal rack.
I'd take $90 plus shipping. Shipping from Japan is expensive around $70, so I'd pay half of it. In total you'd pay $125 shipped via Postal EMS, fastest, economical and safest service. PayPal is acceptable.
Jack Isomura