Steve,
I purchased an MFG 19 last year and it too, had no rudder. I posted the same question here and got loads of responses which you can probably find by scrolling to last fall on this forum.
What I ended up doing was this...
I built my own using 1" oak boards which I shaped to make the portion that the pins hook to the transom, I then purchased a set of rudders from a Hobie Cat on Ebay, which I fastened between the oak. I then purchased a rudder, shorter than the original which comes with most MFG's.
It was a lot of work, but came out very well with the rudder being nearly as low as the bottom of the keel and adjustable as well.
If you like I can see if I can take a picture and send it here, I know people in the past had problems sending stuff, so I'm not sure if it will work.
Like you, I am still working on mine and hope to have it in the water next summer (2011) it is sea worthy now, but I'm working on the interior and adding loads of extras, both on the boat and trailer.
Hope this helps some,
Tony