First introduced in 1962, the Gladiator designations were J200 (short wheelbase trucks, up to mid 1965); J2000; J300 (long wheelbase trucks, up to mid 1965); J3000; and J4000, the first model with the longer 131-inch (3,300 mm) wheelbase.
Gladiators were available in RWD and 4WD, and came either with a solid front axle, or independent front suspension with optional dual rear wheels.
Gladiator trucks were available in the following configurations: Cab and Chassis; Wrecker; Stake Bed; and chassis-mounted campers with extended wheelbases. (See the Dually Registry listed in the links below for more information).
Gladiator bed variations were: Townside, Thriftside (a “step-side”), and Stake Bed.
The Gladiator name was dropped after 1971, after which the line was known simply as the Jeep pickup. The pickups were designated as J2000 and J4000 models until 1973, then J10 and J20 models from 1974 to 1988. https://jeep.fandom.com/wiki/Jeep_Gladiator_(Original)