Fellow Captains,I understand the model differences between a 737-100, 200, 200 Adv, 300, etc. But, do you know what's the difference between a 737-201/Adv, 737-229/Adv, 737-222, 737-228/Adv, etc. I'm refering to the -2xx part. What does it denote? Dave Vega

The last two digits represent Boeing's customer number. This will be indicative of who the aircraft was originally configured for, not necessarily who it was actually sold to.Doug

Thank you Doug. Is there a way to know the engine variant on a 737-200 by it's designation? Dave Vega

The 737-100 and 200 have the older low bypass ratio engines or "straight pipes" everything after that has the larger high bypass ratio engines, usually CFM-56's I believe and they have the characterisitc large round and shorter nacelle. I believe the -200 used different variants of the Pratt and Whitney JT8D.Hornit

Thanks Hornit. Yes, the 737-200 started with the JT8D-9 (14,500lbs thrust). The 737-200 Advanced went to the JT8D-15 (15,500lbs thrust), and newer models were released with the less noisy JT8D-17 (16,000lbs thrust) and JT8D-17R (17,400lbs thrust). Once can almost tell by the engine desination the max thrust level, but I one can't by the aircraft model. At first I wondered if the last three number indicated engine performance, but apparently they only designate who the aircraft was delivered to. Take care,Dave Vega