| 404's for the 1600 too.    The 64 is the same thread/heat range/ thread 
reach, BUT the 64 is an extended tip plug Take a look at the two together at 
the parts store and you'll see what I mean. Your roadster will want the 404. 
I'm surprised the catalogs are showing it that way. I dug out a fairly 
current autolite catalog (1998) and BOY it is sketchy. They may be referring 
to the L-16. I also checked a handy NGK & Champion catalog and they dont even 
list the 311's.  (NGK equiv of 404 is a BR6ES btw)
 FWIW, 
Laurie :-)
70 SPL311
69 SRL311
Chandler, AZ
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