Hey, we have 1990 k-planes which I assume are 280 style as they are about 18inches. I have heard of people switching from the 280 to 380 style plane. I thought the 380 style was 24 inches, but on the merc site it shows the 380s as 30in? If possible we would like to switch to the 30in long tabs. Is this possible to switch just the "plates", and what all is involved? Is there any other manufacturer with larger plates that will switch out with the 280 plates? Lastly, where can I order two 30in plates to fit in place of our 280 style(k-plane or not), unless someone on the board has a couple they are wanting to get rid of...Thanks in advance for your time and help.

Yes you can switch them out. All you do is remove the two pins and switch the plates..... I bought a set on this site used.