I tow around 18-20K with my slightly modified(fueling box and 4" exhaust) 99 3500 C&C. I have low miles,around 45000 on my truck, but if it moves it is towing heavy! If mine cracks after warranty ,I can assure you I will fill it with a good dose of LIQUID GLASS (Sodiam Silicate) that anybody can get at the drug store to "fix " the leak. (Be sure to not route it through the radiator while it is in the block because it will plug the rad. up) I will then spray paint the outside of the block with flat or semi flat black paint(which ever matches the best) and promptly sell it or trade it because it dosen't make economic sense to pay the entire cost of block replacement by myself on a 1999 model truck. I really hate to "pass along the problem", but I hate worse to lose all the money. Cummins SHOULD recall ALL of these blocks and replace them if the owners want them to be replaced!!!!! I really wish so much that someone would/will start a class action lawsuit against Chrysler and/or Cummins. I don't think it will happen at this point,however, because time is slowly ticking by and the affected trucks with the "53" blocks are getting older and many have been traded by the original owner or wrecked/salvaged. Chrysler/Cummins are counting on the time factor to distance themselves from the date(s) of this problem. If there was going to be a class action lawsuit, IMHO it should have been started as soon as the problem was discovered.