Man, I'd love one of these! Much cooler then the more common end dumps. But to stay true to the prototype, I'd stick to hydraulics! These cylinders do not leak like the telescoping rams for end ups, which is a bonus, in my opinion. On the downside, now the tractor should have a wet kit to run the side dump, but I am sure a full contained hydraulic system could be fit to the trailer.
One thing I do want is a replica of a Jet dump trailer. They mount their cylinders on a trunnion, which stops the sudden acelleration of a side dump trailer, as the cylinders pivot near the end of the trailer's side dump travel.
If anyone can pull this off, it'd be you Freddy! Go for it! But remember us 1/16 scale Wedico guys too.
