The Timberwolf is a smaller, more compact ATV designed for recreational use, while the Big Bear is a larger, more powerful ATV designed for utility tasks and off-road riding. As a result, the Timberwolf and Big Bear have different rear ends that are specifically designed for their respective ATVs.
The Timberwolf has a solid rear axle with a swingarm-type suspension, while the Big Bear has an independent rear suspension with a differential and axles. This difference in rear end design means that the Timberwolf's rear end will not fit the Big Bear without significant modifications.