China's universal armored chassis program began with the Kangaroo fully-tracked APC, but its origins trace back to the development of the Wolf tank.

In 1930, when the fifteen-ton Wolf tank's development proposal was brought to the table, Chen Ke introduced his long-conceived universal chassis concept at the design conference. Since Chinese tank design was still in its infancy, he did not force the initiative through. Chen Ke merely told the assembled designers that the universal chassis would be the direction for China's armored forces over the next decade, and they should prepare accordingly when developing new tanks.

At that time, the Fox tank's design was already complete and had entered mass production. At the meeting, someone proposed — in an obvious attempt to curry favor with Chen Ke — that the new Wolf tank's chassis components should be made interchangeable with the Fox's wherever possible. Chen Ke rejected this on the spot:

"You should be looking forward, not backward. The Fox is a product that will be obsolete in a few years. The Wolf is merely a transitional product. If you're thinking about commonality, it should be with the 20-ton and 25-ton vehicles that will be developed in the future."

The result of Chen Ke's directive was that the Wolf tank's road wheels were made significantly wider than the Fox's. When Gao Bupang later designed the Wolf's scaled-up version — the Panda — he directly copied the Wolf's road wheels. Even the Cloud Leopard used the Wolf's road wheels. The Wolf's road wheels were also employed on the famous Kangaroo. Not until the Elephant — entering service near the war's end — required entirely new road wheels to handle its weight exceeding 45 tons.

The vehicle that truly fulfilled the universal chassis specification was the Kangaroo series. The first-generation Kangaroo could essentially be viewed as a front-engine version of the Wolf. Gao Bupang — by then already famous for his "shamelessness" — after his Flying Squirrel tank lost the competition to Lin Pingzhi's Wolf, seized the moment while Lin Pingzhi was still focused on perfecting the Wolf's design. He brazenly took the existing Wolf design, moved the engine to the front, redesigned the transmission accordingly, and — with modifications here and there — turned it into his own creation. The first-generation Kangaroo's chassis shared a remarkable 60% parts commonality with the Wolf — even surpassing the Panda, which was the Wolf's scaled-up version.

The first-generation Kangaroo had only four pairs of road wheels. As needs evolved, the hull was continually lengthened and chassis weight capacity increased. By the third generation, an additional pair of road wheels was added — from four to five pairs — with weight rising to 20 tons. By the fifth generation in the latter stages of the war, weight reached 25 tons. The fourth generation was a half-track variant: a wheeled front section was added to house a new engine and expand the chassis's load capacity for heavier equipment and more ammunition, though this was a highly controversial derivative.

Starting with the Panda, five pairs of road wheels became the signature of China's WWII armored forces — only changing with the arrival of the Elephant, the "heretic" with one extra pair.

The derivative vehicles spawned from the Kangaroo chassis mounted virtually every artillery piece in the Chinese military's arsenal: 80mm through 210mm mortars; 75mm, 90mm, 105mm, and 155mm light howitzers; even 105mm and 155mm heavy howitzers were forced onto the chassis. Every anti-tank gun except the 105mm, all calibers of anti-aircraft guns, and all calibers of recoilless rifles — 75mm, 90mm, and 105mm — were mounted.

These derivatives included both factory-produced vehicles built to front-line requisitions and field-modified conversions improvised by front-line maintenance crews according to battlefield needs. The variety was staggering, the coverage spanning every branch of the armored forces.

Beyond serving as infantry fighting vehicles, Kangaroo derivatives fulfilled roles as light tanks, amphibious tanks, anti-aircraft tanks, tank destroyers, self-propelled howitzers, and self-propelled anti-tank guns — touching every armored specialty. It was the most extensive derivative vehicle family among all WWII Chinese tanks.

The Kangaroo series' derivatives were employed widely throughout the Chinese military in WWII, but combat also exposed many problems.

The greatest issue was excessively thin armor. All self-propelled guns and anti-aircraft vehicles could at best withstand enemy machine gun fire; shell protection was limited to shrapnel resistance. This was an inherent limitation of the Kangaroo-type light chassis. These derivatives were consequently ill-suited for front-line assault alongside tanks under the heaviest enemy fire.

Therefore, apart from the Thylacine (used as a light tank) and the Kangaroo IFV (used for troop transport), most derivative variants were assigned to artillery units or positioned in relatively safer rear areas, subordinated to infantry for supporting fire missions, rarely charging at the very front.

The vehicles that did storm the front lines as assault guns and self-propelled artillery — braving enemy fire for close-range armored support — were derivatives of the Panda and Cloud Leopard medium tanks.

Though the Panda chassis had many derivative types, only a few were mass-produced for widespread deployment, primarily because its derivatives were positioned as front-line combat vehicles from the start. The Panda chassis was chosen specifically for its robust defensive protection.

Since the Panda's turret could directly accommodate a 105mm howitzer, the "Bear" self-propelled gun was WWII China's only self-propelled artillery with a 360-degree-rotating turret. In combat, it charged alongside Pandas and Cloud Leopards at the very front, providing the most direct close-range fire support. Well-protected, highly mobile, and packing powerful high-explosive shells, it was beloved by front-line troops. When supply lines failed, many front-line tank maintenance crews simply assembled their own Bears from available parts. As a result, just how many Bears WWII Chinese armored forces ultimately possessed remains unknown — estimates range from roughly 980 to just over 1,000.

Some elite armored divisions — equipped exclusively with Cloud Leopard chassis — also performed similar conversions on their Cloud Leopards. However, since these were unofficial front-line modifications, the exact numbers are unknown, and this Cloud Leopard derivative never received an official designation.

Another important use of the Panda chassis was as the platform for self-propelled anti-aircraft vehicles. Every small-caliber AA gun deployed by the Chinese military was at some point tested or employed in combat on Panda chassis.

Combat is the ultimate testing ground for weapons performance and design philosophy. Many of the Kangaroo series' diverse derivatives were eliminated after combat evaluation. Consequently, Panda chassis derivatives numbered half as many types as Kangaroo derivatives. By the time the Cloud Leopard chassis was reached, the family had been ruthlessly pruned to just two: the Iron Leopard for fire support and the Flying Leopard for anti-aircraft warfare.

Panda and Cloud Leopard chassis derivatives fought at the absolute front line, charging under enemy anti-tank fire. Protective capability was the paramount priority.

Though the Panda chassis yielded many anti-aircraft vehicle types, by mid-1943 — after combat evaluation — only two remained in mass production: the Flying Bear I anti-aircraft vehicle (with twin 37mm Bofors guns) and the Flying Bear II (with a 30mm Gatling cannon). The 20mm anti-aircraft caliber was retired.

The Cloud Leopard chassis's "Flying Leopard" anti-aircraft tank differed little from the "Flying Bear" in performance, merely offering slightly better protection and more ammunition. The Flying Leopard and Iron Leopard were generally assigned only to elite Guards Armored Divisions equipped exclusively with Cloud Leopard chassis. By the war's later stages, as technology advanced and battlefield conditions evolved, the proportion of pure-Cloud-Leopard armored divisions gradually increased to 30%.

The Spotted Leopard tank destroyer — though only four prototypes were built for testing and improvement — had its production contingency plans brought to the agenda when the M26 and Centurion appeared in the war's final phase. Manufacturers even received production quotas. But the war's end killed the project in its cradle.

Panda chassis anti-aircraft tank production exceeded 2,000 units during WWII. Each armored division typically received twelve to eighteen anti-aircraft tanks for battlefield air defense.

During WWII, Chinese armored forces early appreciated the logistical and maintenance advantages of the universal chassis. The British, by contrast — having developed a bewildering array of tank chassis during the war — looked rather disheveled by comparison. However, in practice, the Chinese Army also recognized the trouble caused by excessive diversity in artillery calibers. From the mid-to-late war onward, small-caliber guns were gradually reduced. Support artillery was standardized as much as possible to 105mm and 155mm. The 75mm infantry gun/light howitzer was progressively replaced by lighter mortars and recoilless rifles. As for 20mm anti-aircraft guns — with aircraft flying ever higher, their performance proved inadequate. After 1943, they were withdrawn from front-line service and replaced by the more powerful 30mm autocannon.