1.6 to 1.7 world compatibaly issue

Has anyone gotten a world with a 1.6 version of their mod to correctly load in an 1.7 environment?

Mine works as it should with a fresh 1.7 world, but if I load a 1.6 world it acts up.

- The Block is removed from the world.

- The ItemBlock is not using the blocks renderer, rather its using the standard item renderer.

- Item.getItemFromBlock() returns null, indicating the block has no item mapped to it anymore.

It should work, the modid and registered block name are identical, and so are the class names.

Even the code doing the registration is basically identical.

1.6

Values.blockEnderTank = new BlockEnderTank(idEnderTank);
GameRegistry.registerBlock(Values.blockEnderTank, ItemBlockEnderTank.class, "blockEnderTank");
Values.itemEnderBucket = new ItemEnderBucket(idEnderBucket - 256);
GameRegistry.registerItem(Values.itemEnderBucket, "itemEnderBucket");

1.7

Values.blockEnderTank = new BlockEnderTank();
GameRegistry.registerBlock(Values.blockEnderTank, ItemBlockEnderTank.class, "blockEnderTank");
Values.itemEnderBucket = new ItemEnderBucket();
GameRegistry.registerItem(Values.itemEnderBucket, "itemEnderBucket");

Reading the conversion output, it only has 3 entries for my stuff, everything else is minecraft blocks and items.

Found item id mismatch EnderTanks:itemEnderBucket : 4096 5380

Found item id mismatch EnderTanks:blockEnderTank : 165 2380

Injecting new block EnderTanks:blockEnderTank