The PTO rpm is different, etc, etc on the 400. Good tractor but equipment only works on the 400 without moding something. But-what is the reason for the collection? With our collections (fathers/families). We have the first year of every lettered series two cylinder JD tractor, First year of the 1010, 3010, 4010, 4020, 3020, Last year of the 330, 830. First years of the A, G and 3020 high crop tractors. All of the pedel tractors and bikes. All first year patio tractors (16) and related equipmetnt. Have a reason or method to the collection-stick with it.