Cox produced a very large number of the "La Cucaracha" in various forms. Its IFC chassis is all four forms (yes, four!) also equipped the Chaparral 2E RTR and IFC kit, the Chaparral 2D, Cheetah and as the "Ferrari GT" (Dino) kits, and the Ferrari RTR models. Well over ONE MILLION were produced.
There are serious issues with the IFC chassis engineering, mostly a question of lack of rigidity in the rear-axle brackets, which bend inwards and derange the gear mesh. A simple fix that will not alter the originality of the car, is the fabrication of a brass "bridge" that can be fitted inside the bearings mounts and just clearing the crown gear, elegantly resolving this problem.
Another issue is the distance between the motor and the crown gear, requiring a very long pinion, that is not that easy to find today. Last, in the case of the Chaparral 2E (kit or RTR versions), the plastic pieces allowing the motor to rotate and actuate the wing are quickly deformed, the pinion then chews at them, again destroying the gear mesh.
The La Cucaracha was first issued in 1966 with an orange translucent body and the TTX150 motor with red wire. Later that year, the chassis was modified with side mounts for "other" bodies, and the orange body molded in a more opaque color, while the front wheels were updated with different built-in bearings, the armature now with brown wire of a larger gauge. In 1967, as the body mold was modified for use in the "La Cucaracha GT" or "SuperCuc" models, molded in blue, the subsequent La Cucaracha roadsters (still molded in orange polypropylene) benefited from the added and period-fashionable front fins (hey, you NEED down force, don't you? ) and of the mechanical updates, new black-sponge rears on setscrew wheels and the Cox Hong-Kong sourced NASCAR motor.
ANY other "Cuc" body colors came from aftermarket bodies sold six on a large card, but were NEVER offered as factory assembled RTRs (don't let an unscrupulous seller telling you how "rare" they are, as they are not!). Colors are metallic purple, dark green, dark blue, light blue, dark red, rose and gold. The orange bodies were NEVER sold separately, and all the colors except the purple ones were not sold in individual packaging, packed on a standard body card.
The SuperCuc, modified Cuc and Lil'Cuc (the 1/32 scale version) were offered through 1969. I would say that THOUSANDS have survived in fair to pristine condition.