1. Duration: The length of the warranty is one of the most important factors to consider. A good transmission warranty should offer at least a 12-month period, but some can extend up to 10 years or more.

2. Coverage: Check the level of coverage included in the warranty. A comprehensive transmission warranty should cover all major mechanical components of the transmission, including parts and labor.

3. Transferability: If you plan to sell your car, check if the warranty is transferable to the new owner. This is an important factor to consider because it adds resale value to your car.

4. Restrictions: Some warranties may have certain restrictions that limit their coverage. For example, a warranty may be voided if you modify your car or use it for racing purposes. Make sure you read the fine print before you purchase the warranty.

5. Cost: A good transmission warranty will come at a cost, so make sure you compare prices from different providers to get the best deal. Look for a provider who offers flexible payment options and reasonable deductibles.

6. Reputation: Do your research and check the reputation of the warranty provider. Look for customer reviews online and ask for recommendations from trusted friends or family members. Choose a company with a proven track record of providing quality service and honoring their warranties.