There are two types of gladii that are accepted for use in the era the Legio VI recreates.  The Mainz and Pompeii types. 

Delos Blade:

            While this type was not used during the era that Legio VI recreates it was in common use during the first half of the first century.  The Hispaniensis blade (named after the encounter of this blade during the conquest of Spain) was phased out during the last half of the first century BC.  The smallest examples found were from 622 mm to 661 mm in length and 40mm to 45 mm at the broadest point.  The largest example found were 760 mm in length and 57 mm wide.

Mainz Blade: 

            The Delos type was believed to be phased out by the Mainz type during the reign of Augustus.  The Mainz blade (named after examples excavated in Mainz, Germany) was phased out during the middle of the first century AD.  Examples were found in Britain suggesting that the Mainz type remand in use up until the invasion of Britain, AD 43.  The common length of this type varied from 400 mm to 550 mm (excluding tang), and the common width taper from 54-75 mm to 48-60 mm.  There is a similar type of gladii to the Mainz and that is the Fulham.  Really the only difference is the shape of the blade, which could be the soldier sharpening it to much?

Pompeii Blade:

            The Mainz type was believed to be phased out by Pompeii type during the middle of the first century AD.  The Pompeii type (named for examples excavated in the ruins of Pompeii, Italy) was phased out for long ‘spatha’ type swords during the last second century and third century AD.  The common length of this type varied from 420 mm to 500 mm and the common width between 42 mm and 55 mm. 

Wearing the Gladius:

For legionary it is proper to wear the gladius on the right.  It is accepted, that with the wearing of the lorica segmentata, a baldric is required to hang the gladius.  There have been no evidence that the baldric had any fasteners of kind, since it could be slip over the head and shoulder.  Although attempts to identify cavalry harness fasteners as baldric fittings continue, despite the differences in decoration between infantry and cavalry equipment. 

The gladius may also be suspended from it own belt, a second belt.  This was more common with earlier periods and only worn with the lorica hamata.  This belt would have no apron, and could consist of two frogs to suspend the gladius like the pugio or not.  If no frogs were used using leather straps put threw the rings on the scabbard and around the belt would attach the gladius

Only legionary with the rank of Centurion or better wore there gladius on the left. 

Here is what “Roman Military Equipment: From the Punic Wars to the Fall of Rome” by M.C. Bishop & J.C.N. Coulston has to say about the Mainz and Pompeii gladii.

Contrary to popular belief, the term “gladius” can mean any sword and is certainly not specific to short weapons.  The infantry sword underwent an important metamorphosis some time after the middle of the 1^st century AD.  The familiar long-pointed, taper-bladed weapon of the Republic, the so-called gladius Hispaniensis (which survived as the ‘Mainz’ type), was phased out in favor of the parallel-edged, short pointed replacement (the “Pompeii” type).  These two swords are, it has been suggested, symptomatic of a change in the style of Roman fighting.  Examples of the Mainz type sword (so-called because so many examples come from the Rhine at Mainz) and its associated scabbard fittings are found throughout the first half of the century and it was clearly still in use at the time of the invasion of Britain in AD 43.  The blade (excluding tang)vary between 400 mm and 550 mm in length and blade widths taper from something like 54-75 mm to 48-60 mm, with the length of point varying between 96 and 200 mm.  The handle assembly consisted of a handguard, an octagonal-sectioned handgrip usually made from a cow longbone, and then a pommel of slightly flattened ovoid appearance.  The pommel and handguard were often made of wood, as example from Vindonissa show, but could also be of bone or ivory.  These pieces were held onto the tang by a copper-alloy rivet.  The sword from Rheingonheim had a silver plated wooden handle and the rivet originally possessed a ‘small ring from a bronze chain’, recalling a gladiator relief from Rome where the sword is suspended form the gladiator’s wrist by a cord or chain.

The parallel-edged Pompeii type (with blade lengths between 420 and 500 mm and widths between 42 and 55 mm) was named after four examples found at Pompeii with the well-known terminus ante quem of AD 79.  Examples of the weapon and its scabbard-fittings give a rather different distribution by comparison with the Mainz-type sword and one piece of scabbard from Verulamium is dated to before the Boudican revolt (AD 60/1), possibly the earliest  archaeological manifestation of the weapon.  Finds of Pompeii-type scabbard-fittings from Wadden Hill seem to belong to some time before AD 64, although the earlier terminal date for Hod Hill (which has also produced Pompeii-type fittings) has been questioned.  The handle assemblies differ markedly from those of the Mainz-type sword, with the handguard now more pronounced and the pommel resembling a flattened sphere.