How can you tell what gears in a front end without splitting the casing?

1. Check the vehicle's identification number (VIN). The VIN is a unique code that identifies a vehicle. It can be found on the vehicle's registration or insurance card, or on the driver's side door jamb. The VIN can be used to look up the vehicle's specifications, including the front end gear ratio.

2. Measure the front and rear axle ratios. This can be done by jacking up the vehicle and rotating one of the tires until the axle turns one full revolution. Then, count the number of times the driveshaft turns. The driveshaft will turn the same number of times as the ring gear in the differential. The front and rear axle ratios will be listed as whole numbers that are a multiple of 1:1 (e.g., 3.55:1, 4.10:1).

3. Check the service tag. The service tag is a metal tag that is typically attached to the differential housing. The service tag will list the vehicle's front end gear ratio.

4. Consult a mechanic. If you are still unable to determine the front end gear ratio, you can consult a mechanic. A mechanic will be able to look up the vehicle's specifications or measure the front and rear axle ratios to determine the gear ratio.