Going Newark to San Diego. Flight says it's a 737 800 series but when I go on guru there are many of these. How does one know what series a flight is? Flight is in November..

You really can't tell for sure, but the differences aren't all that great the less desirable seats are pretty much the same.

Version 1 (14/141) on Seatguru can only be found on planes based in Guam. You won't be flying one for EWR-SAN.

Version 3 (16/141) is the most common type, with about 80 of them.

Version 2 (16/144) is the dozen of so that were delivered in 2008. They have 3 extra seats in 29ABC. But until early 2009 when CO start installing LiveTV, these planes don't have any inflight entertainment at all. CO right now tend to not put them on the trans-con.

Version 4 (20/132) is the "mid-lav" version with more first class and the lavatory in the middle. There are only about 20 of these. But if you look at your seatmap and see 5 rows of FC, then that's your plane.

More detailed breakdown, and some correction. As for 7/28/08, there were:

Version 1 (14/141) - 9 aircrafts
Version 2 (16/144) - 8 aircrafts
Version 3 (16/141) - 85 aircrafts
Version 4 (20/132) - 12 aircrafts
Total: 114

Between 7/28/08 and end of year, there would be three more Version 2 deliveries. Not sure how many of those three have been delivered yet.

rkkwan..you are amazing. Thanks for the info.