Harvester

large, slow, and defenseless, the Harvester is still incredibly important for the health of your army and base. This large truck scours the Tiberium fields to dredge the precious mineral and return it to your base where you use it to create units and structures. In short, the harvester is your main source of money, so it's also your main sourse of military and defensive power. The harvester can hold five units or any Blue or Green Tiberium , or any combination of two. Despite their lack of speed pr defenses. Harvester are faily durable and can take a significant amount of damage before being destroyed. Against infantry, they can be used as steamrollers, crushing Nod ground troops like ants.

Wolverine

The Wolverine is part man, part machine. Basically, a light infantryman suits up in the Wolverine armor becoming more durable and mush faster. Wolverines can be used similarly to infantry but unlike regular troops Wolverines are created in a War Factory. Although they hold up well against unarmored opponents. Wolverines are susceptible to heavy-weapons fire. Their speed makes them excellent base defense units; Wolverines  can be redeployed quickly to critical points. For the same reason, Wolverines make great strike troops because they can rapidly march into the heart of the enemy base and attack with surgical precision.

Titan

The Titan fills the role of a normal tank in the GDI army. Instead of trends, this large assault weapon is mounted on two jointed legs--the Titan walks rather than rolls across the battlefield. Titans are armed with powerful weapons capable of quickly blasting through armored units and structures and they have weaponry that makes them relatively effective against softer targets. Because of their versatility. Titans will make up the bulk of GDI forces. they can stomp on infantry that tanks and other heavy vehicles would drive over. most important, Titans have excellent range with their weapons and can destroy many Nod base defense, like Lasers, from outside the enemy's range.

APC

Use the amphibious armored personnel carrier[APC] to move troops from place to place efficeintly. This units has no way to attack and no way to defend other than its ability to flee. Not very speedy on land, the APC is very fast in water. and is best suited for amphibious assaults against Nod forces. You can place five infantryman of any type  and combination--Disc throwers, Medics, Engineers or Ghoststalker in an APC.

Mobile Sensor Array

Nod forces rely heavily on surprise for success which makes them difficult to deal with a times. The MSA is the best defense against this Nod Strategy. when deployed this large vehicle spots cloaked or subterranean Nod units with  in a large radius. Although not revealed on the radar map. the location of these enemy units are revealed on the main game screen. this information helps you prepare for the arrival of the underground units or attack the stealth units before they are ready to defend themselves.
As its name implied, you can move the MSA to different points on the battlefield to spot hidden Nod defenses. Have them guard approaches on your base too.

Hover MRLS

Another  innovative GDI departure from tank technology is the mobile rocket launching system [MRLS]. A hovercraft this unit flies a few feet above the ground or water, so its capable of amphibious assaults. Use them to provide cover for APC when attacking a nod base. MRLS are also excellent in conjunction with other GDI units on the attack because their rockets allow powerful strikes form long distances. Don't have them lead an attack. though; their fragile nature makes them better supports units, keep them outside of the enemy's range while  hitting with power.

Disruptors are the most difficult units to use effectively in Tiberium Sun. Not nearly as fast as other GDI vehicles. Disruptors are especially dangerous to your won forces in the back ranks of an attack. Their main strength and main use is in the powerful weaponry they mount. The disruptor cannon destroy any unit or structure it hits by literally shaking it apart. Unfortunately the weapon can not distinguish between friend and foe so an ally that crosses the beam's path will sustain significant damage. Disruptors are fragile vehicles making them a poor choice for leading an assault. They are best used in flanking attacks where they can avoid the brunt for enemy fire and bring the full power of their weapon to bear strictly on Nod units.

Mammoth Mk. II

The newest piece of experimental weaponry in the GDI arsenal is the Mammoth Mk. II. A four legged vehicle, this huge mech can crush Nod assaults single-handedly and with limited support can smash through a Nod base leaving only rubble in its wake. The Mammoth is armed with twin rail guns as well as antiaircraft missiles, so it's well-protected against both ground and air assaults. And if necessary it can slowly repair itself in the field. Because of the experimental nature you can possess one Mammoth Mk. II at a time, buy you don't need more than that.

MCV

The mobile construction vehicle [MCV] is a large lumbering machine. When deployed this vehicle transforms into a construction yard-- the first unit of a base and one of the most critical. In later missions, you gain the ability to create your won MCVs but generally you receive them at the beginning of missions as way to establish your main base. Use MCVs to back up your main constructions yard if it gets destroyed or to start a second base.