A: Some of the more common ones are:
AT = Automatic Transmission OR All-Terrain (tires)
MT = Manual Transmission OR Mud-Terrain (tires)
TC = Transfer Case OR Torque Converter
SYE= Slip Yoke Eliminator (also called a fixed-yoke conversion or a short shaft kit)
SA = Solid Axle
SFA= Solid Front Axle
SRA= Solid Rear Axle
CA = Control Arm
LCA= Lower Control Arm
UCA= Upper Control Arm
IFS= Independent Front Suspension
IRS= Independent Rear Suspension
SOA= Spring Over Axle
SUA= Spring Under Axle
BPE= Bar Pin Eliminator
DPA= Drop Pitman Arm
ECU= Engine Control Unit
TCU= Transmission Control Unit
TB = Throttle Body
FI = Fuel Injection
MPI= Multi-Port fuel Injection
TPS= Throttle Position Sensor
IAS= Idle Air Stepper motor
CPS= Crankshaft Position Sensor
MAP= Manifold Absolute Pressure(sensor)
O2 = Oxygen (sensor)
NSS= Neutral Safety Switch (sometimes called Neutral Start Switch)
CCV= Crank Case Vent
PCV= Positive Case Vent
BB= Budget Boost (typically refering to a 2" or less spring (or coil spacer) lift priced at or below about $200)