Chevrolet Repair: 77 chevy pickup drivetrain, pickup 4x4, google search

Question
My son needs a 30 spline yoke for his '77 chevy 1/2 ton pickup 4x4.(k10)  What is the difference between a centering yoke, weld yoke and an H yoke.  I am not sure which one to get for his truck.  We are having his driveshaft repaired and cannot find this yoke anywhere.

Thank you,
Jeanne

Answer
Hello Jeanne,
I tried to send an answer yesterday but it wouldn't go.
I searched Google.com for GM centerink yoke, and got some very good links.

http://www.rockforddriveline.com/3_SlipYokes.pdf

This link is one I pulled out that shows how to decide what to order. It is from a Rockford site,

http://www.rockforddriveline.com/new.htm

and has descriptions of all the parts. That SlipYokes page is from this second link.
Look through some of the others from the google search, and it should help you out.

Van