I received mine this week and took only about ten minutes to put it in. Just pulled the clip and pin off the bottom and pulled out the old spring and stuffed the new one in. A little play now upon initial depression, but pedal feel has improved.

Actually, I'm looking at this again and I think the ID on the fastenal spring might be a little too tight where the hat and lower piston part sit inside.

I ordered 4 springs from Century Spring that are definitely the right size though so I'll have extras around. I should have just done that from the start but I didn't want to have to get more than one as Century has a minimum order size...

Thats pretty much the problem, most places want you to order a minimum quantity.

bluenoser, if you are planning on ordering extra springs and selling them to people, please do not use my threads. I would love to help everyone out and keep organizing these but I don't have much time at the moment and AK made it very clear that he did not want to do another group buy. I suppose his reasoning is that a normal forum user is not a business so he doesn't want the forums being held liable for selling parts or anything.

The company I got the spring from is called LeeSpring, this is the spring here:

Lee Spring

Ordering 1 spring from them directly is pretty retarded however, it costs about $18 + shipping + $20 surcharge for ordering below minimum quantity, hence why I organized the group buys.

I would suggest using the spring dimensions listed on the page and trying to find something that's close but doesn't require the same ordering restrictions.
Stock rate is about 330lb/in so this particular spring is about 75% softer.

These are the dimensions that matter for size:

Outside Diameter: 1.23"
Inside Diameter: 0.87"
Free Length: 2.4"

Anything that's close to this will be fine.