Rich, Dan, and All: I will try not to belabor this topic. (Scared to!!) 1. My copy of the 1955 AMA Specs is also the 2-15-55. I made a copy of it while at Chrysler in the '70s and would have certainly tryed to get the latest issue. Doesn't mean I did, though. 2. The 355 300B utilized a higher compression HEAD. The confidential bulletin to the dealers is dated June 13, 1956, and states the new heads are 10 to1. It also states the heads are identified by part "1730369-1". They are not interchangeable with the 9.0 1955 C300 heads. They are to be used only with AGR-31 or colder plugs with ignition timing set from 0 degrees to 4 degrees BTDC "depending upon octane rating of fuel available". Wonder if these had a PN riveted on them as Owen surmised his 390HP "C" may have. Likely we will never know. 3. Chrysler microfilm records show only ONE C300 being built with a manual (code 1) Tranny. That car (built in June) did go to Kiekhaefer, who apparently converted it to a 300B for the next season! How many other C300s were converted by owners to manual shift is anybody's guess. 4. Regarding octane, Hemis (sphereical segment combustion chambers) are more tolerant of lower octane because they don't "squish" the fuel-air mixture as unevenly as other configurations. I can only relate my personal experience of running my 300C in the sixties on Sunoco 190 with no problems. Ran right well too. The car had its heads milled also, as I was at one time going to make it into a 390 HP version since I had one of the Isky cams used in the Daytona Trials. However, sanity prevailed and I bought a stock 300C cam from Chrysler and "did the right thing". 300ly, Gil Cunningham Tallahassee, FL **************Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food. (http://food.aol.com/dinner-tonight?NCID=aolfod00030000000001) [Non-text portions of this message have been removed] ------------------------------------ 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 For archives go to http://www.forwardlook.net/300-archive/Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: mailto:Chrysler300-digest@xxxxxxxxxxxxxxx mailto:Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> 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/