Features of the “Advanced 737”:
   New High-lift system
     Extended-span inboard Krueger flaps;
     Wide nacelle strut;
     Smooth fixed leading edge;
     Slat positioning;
     Trailing-edge flap seals.

   Improved Stopping:
     New metering pin for smoother landing;
     Auto brake system;
     Advanced anti-skid system;
     Nose wheel brakes available.

   Improved engines:
     JT8D-15 with 15,500 lbs., later -17 (17k) became an option.

   New “wide wide body” interior.
   Gross weight increase: 5,000 lbs., or more.
   Development started in 1969, with certification 1971

SP 177 autoflight system became available late 1970’s as an option, while SP 77 remained available until at least 1985. The -177 offered many advantages including altitude capture, up to autoland capability.

When a customer orders a Boeing, an id is assigned. For example, Southwest (USA) is “H4”; all of their aircraft will be listed as 737-2H4 as a -200, -3H4 if a -300, etc.  Original United Airlines is “22”, or 737-222, -322, -522. But these two examples will have a different “standard” which will likely be different than a Boeing base standard. A customer can order many, many specifics: Logo lights; different gross weights; engine; SP-77 vs. -177 and so on. The thought is to have a standardized flightdeck for the crew and operation  –all airplanes for that operator are the same. However, some airlines will short-term lease, or acquire aircraft from multiple operators, making it a more difficult and eliminating what is “standard”.

Perhaps it has been stated somewhere elsewhere which specific 737 this model represents. While many features and system operations carry between the variants, there are differences, too. When making a statement of “standard”, or “incorrect” the author should be cautious due to operator changes.

Also, all 737-100 to 500 are considered as “classic” models; -600 to -900 are “NG”, or Next-Generation.

Sean