what is the difference between a longtail bevertail and a godevil? Quality, etc.

The beavertail uses sealed bearings in the lower end, while the Go Devil uses bronze bushings. Also, the BT does not have a center bushing on the shaft, and the GD does. The U-joint/yoke on the BT and GD are different as well. GD uses a pinch-style, while BT uses a set screw. Both are very similar in design and function. All that being said, I ran a 20hp Beavertail for several years (8 years) without problems; just basic maintenance. I have been around Go Devils and can say that personally, I like the way they are made a little better. For one, I was never happy with the "tail whip" associated with my BT. Also, it's hard to beat a product that a company has been manufacturing since 1977. Hope this helps.