The Fleet Status site is:
https://sites.google.com/site/unitedfleetsite/

At the site, you can find information about the interior features, livery, etc., for every plane in United's fleet.

United Airlines Equipment (Aircraft) Codes (via JOSECONLSCREW28)- code refers to type and configuration but not IFE:

pmCO
73S - B737-700 Guam Configuration (12/30/84 Slimline)
73G - B737-700 Slimline (12/36/78 config)
73Y - B737-800 Slimline Config (16/54/96 config)
73U - B737-800 Guam Slimline Configuration (16/42/108 config)
73Q - B737-800 Slimline (16/54/96) with SFP (a/c 3519 and above 16/48/102) 3528 and up Sky Interior, 3532 and up Sky bins
73C - B737-900 Slimline (20/42/117 config)
37X - 737-MAX9 Slimline 20/48/111): Slimline Config (3413-3442 & 3479: 20/42/117), (3443-3478: 20/39/120) (3479 Sky Interior and Space bins)
75B - B757-200 Int'l Config (16/45/108)
75S - B757-200 Int'l Config (16/42/118)
75E - B757-300 Slimline (24/57/156 config)
76S - B767-400ER (39/70/131 with Y crew mod)
78V - B787-8 (36/70/113 config)
78Z - B787-9 (48/88/116 config)
77Y - B777-200ER ("Version 2"/ 50/72/145 config)
77E - B777-200ER Polaris/PP (50/24/46/156)

pmUA
19S - A319 version 1 (8/42/78 config)
19C - A319 version 2 (ex-CZ frames) (8/42/78 config), different lavs
19F - A319 version 1 (12/36/78 config)
19G - A319 version 2 (12/36/78 config) (ex-CZ frames) (12/36/78 config)
20S - A320 version 1 (12/42/96 config)
20C - A320 version 2 (ex-CZ frames) (12/42/96 config), different lavs
20F - A320 version ? (16/36/96 config)
37K - B737-900ER (20/39/120 a/c 3801-3810 ) (20/42/117 a/c 3811-3894 Sky - a/c 3895-3899 Space Bins)
75K - B757-200 (formerly known as "ps") (28/42/72 config)
76C - B767-300ER 2-cabin non-Polaris (30J/49E+/135Y config)
76A - B767-300ER Polaris 2 class (30J/46E+/138Y config)
76L - B767-300ER Polaris/PP (46J/22PP/43E+/56Y config)
77G/M - B777-200 Domestic (Versions 3 & 4 / 28F/102E+/234Y config)
77Q - B777-200ER 3-cabin (20xx & 28xx Tail #s) & (27xx Tail#'s) ("Version 1"/ 8F/40J/113E+/108Y config)
77U/N - B777-200ER Polaris/PP (50J/24PP/46E+/156Y)
77X - B777-300ER Polaris/PP (60J/24PP/62E+/204Y)
78J(78X) - B787-10 Polaris/PP 44J/21PP/45E+/199Y config)

Here's what each of the facilities do historically:
Domestic Contract:
LCQ, Airbus heavy/medium maint, Airbus Inductions and mods, 319/320 reconfiguration, 763 paint
MIA, reconfiguration and maintenance, all except 787/777
DLH, Airbus maintenance
SAT 757 maint/reconfiguration, some 763 maintenance
INT, 737 & 757 maint.
TPA, 737 heavy maint, contract, but UA building own hanger
RFD, 777 ADS-B
ILN occasional 763 maint.
Domestic In House:
HOU, 737 heavier maintenance, some shorter mod work
SFO, Airbus D checks, heavy 772 maint, 737NG C checks, other maint.
MCO, 737/757 maintenance, some mods.
IAH, light maint, some mods
SEA, 77W, 787 delivery induction
DEN, IAD, 787 new delivery induction
Paint Facilities
VCV, AMA, CWF, FTW paint
International Contract:
HKG, heavy widebody maint and reconf (also heavy GUM 737 maint); 763/772GE Polaris mods
XMN 772PW Polaris mods, 787 mod, 777/787 heavy maint
PVG, 788 modifications/WiFi, GUM 737 maint
PEK, some widebody maint.

Services ended at:
MCN, PEK, SKF, VQQ

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