alternator shorted out and speedo and tach quit

They aren't related to the alternator unless a fuse blew. The Engine Computer sends a digital signal to the Body Computer which interprets it and sends another digital signal to the instrument cluster which is a computer module itself. Typically if only one or two gauges don't work, it's a problem in the instrument cluster. If the gauges work but stay on "0", it can be a problem in any of those computers.

If the transmission shifts properly, you know the speed sensors, Engine Computer, and Transmission Computer are working properly.

good advise. from others on the internet, i figure it is the cluster circuit board. the u-pull bone yard sells them for $15, except they dont have a compatable caravan in the yard now

Where are you? There's a real nice chain of about two dozen very clean and well-organized yards called "Pull-A-Part" between Ohio and southern Georgia. I've been to 16 of them. A 2002 is a little new for them. On my last visit two years ago, the newest I saw was a '98 Caravan. You can do an internet search to check their inventory at each yard.