Bob and list, Regarding the following: <By the way, HP blocks are a different casting blend than standard blocks -- higher nickel content. HP blocks also were heat treated for stress relief. HP blocks were built in batches, separate from normal blocks, so they were not pulled out of the production line for performance modifications. HP blocks sat in a group in the warehouse until they were pulled for the production line, which is why the date stamp on an engine can be much earlier than the car's build date> I've heard this from a few folks over the years and have never been able to find proof of any difference in the blocks. If they were different, why are the casting numbers the same as 413s used in non-300s? There are several sites that list casting numbers, and at least one site states that there was no difference in the block used in HP 413s. Bob J - To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/