... and here as well.
Twin Tube Classic.pdf
P.S. Dropbox links default to a "dl=0" tag on the end which prevents downloading of the file. It took me awhile to figure that out when I was sending links to people and learning that they weren't working. Changing the tag to "dl=1" solved that problem, as does just deleting the tag altogether as I recall. (When you click on "send a link to this file" you'd expect a link that actually works! )