Manual Transmission Spline Gear and Identification assistance.

[forgeman]

Hey Gang!

I'm in progress of a complete over haul project on a 72' C20 2WD. I've pulled the engine and transmission. Once the transmission was separated from the engine I inspected the spline input gear and noticed that there are "issues". There are hairline cracks on the input spline along with the spline is starting to "corkscrew" ever so slightly. (See Figure 1)

Questions:
Does anyone have a good resource for a replacement spline input?
Is it worth it to tear down and fix or should I search for new?
Can anyone identify this transmission (See Figure 2 for top plate numbers, Figure 3 for bottom plate, Figure 4 is total transmission)?

Thanks for any assistance!!!


Figure 1:


Figure 2:


Figure 3:


Figure 4:



Overall project images (some better overall pictures of the transmission too):
http://picasaweb.google.com/forgeman