I mentioned this earlier in the thread but will mention it again. There dats for sandworm can screw you if you change them and they are definitely resized server side. I changed mine to stones from Dyna when I was doing my Ulhus. I would make it maybe 2 or 3 fights before something would happen and FFXI would just bomb. If you can find a good character model that doesn't crash you out, great. I would just be very careful about it as you can lose items (lost ~6 fangs this way).
Also there are in fact 3 dats that have sandworms, though I think that only 2 of them are for abyssea. Glav, Minicowhoe, and Ulhu are one, while the mini's are another (the mini's aren't small though, they are scaled down server side).