To begin with let's take a closer look at the 1/18 RC Front/Rear Upgraded Differential, a spare part designed for Wltoys A949A959A969A979 RC Cars.
This product boasts the brand name of Wltoys and is identified by the item name of Wltoys A949A959A969A979 Front/Rear Complete Differential, with item number A949-B-28.

In actuality the 1/18 RC Front/Rear Upgraded Differential is a complete differential that provides an upgrade from the stock plastic diffs. This upgraded differential comes fully equipped with metal gear inside and outside, including a planetary gear, making it a durable and long-lasting replacement for the original parts. One potential drawback of this product is that the housing of the bevel gears is not made of metal, but it is still quite sturdy. Overall this differential provides a significant improvement in strength and performance over the original plastic parts.

In other words the main advantage of this upgraded differential is that it is far stronger than the stock plastic diffs that come with the Wltoys A949A959A969A979 RC Cars. It can also be used for the 144001 RC car, although it is essential to check the amount of lubricant before installation. Its only weakness is the non-metal housing of the bevel gears, which may be a concern for some users. Nonetheless, the metal gears inside and outside make up for this drawback ensuring a strong and reliable performance.

Overall I highly recommend the 1/18 RC Front/Rear Upgraded Differential for anyone looking to upgrade their Wltoys A949A959A969A979 RC Car's performance. This product is made of high-quality materials, including fully metal gears, and it provides a significant improvement in strength over the original plastic parts. If you're in the market for a reliable and durable differential that will improve your RC car's performance, the 1/18 RC Front/Rear Upgraded Differential is an excellent choice.