Richard, Last weekend I measured the expansion plug(s) in a spare set of heads I have for my G. They measured 1-3/8". having said that, the plugs were installed in the heads and I was not able to insert the inside calipers in the bore to do a precision measurement. If, as others have posted, some of these plugs are 1/64" larger, 1-3/8" may not be accurate. If it were my car, I would go with 1-3/8" plugs and check the fit. If loose, go 1/64" larger. Bob J ------------------------ Yahoo! Groups Sponsor ---------------------~--> Yahoo! Autos. Everything you need to know about buying or selling a car. FREE Quotes, 360° Tours, Research, Blue Book, Compare Vehicles, Buy Used http://us.click.yahoo.com/kEZsdA/bwnGAA/YiGOAA/8LmulB/TM ---------------------------------------------------------------------~-> 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/