No worries. I did a little digging and it is indeed FL410 for the -600 thru the -900ER. The -100 thru -500 have a service ceiling of FL370 (this is primarily due to better pressurization control in the newer airplanes, and the wing on the NG's was redesigned for optimum of .80 cruise (whereas the older 737's optimum cruise is around .73 to .75) and is slightly different aerodynamically and bigger than on the older airplanes).
This is a really good site for 737 stuff, the link will take you to the limitations page, but there is a ton of more useful stuff on this site:
http://www.b737.org.uk/limitations.htm#Operational

EHAM-YSSY B772LR
ATP, CFI, CFII & MEI, CL30, 727, 737-200, DC-9
FS9, Active Sky 6.5 w/ASG, FSPax