You can order it from http://www.por15.com/puttys.html
Based on m recent experience you'll want to pull the manifold. You'll need to drill 1/8 inch holes at the end of each crack to stop further cracking. Then you'll need to grind a small v groove. Then apply the material.
The material is surpising easy to work with and my first worry that it would run out before setting was not founded.
Best of luck.
S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)