Deere does not use flat rates. On current models they have what is known as MArket Service times. Market Service times are suggested labor times designed to make estimates from, but as with any repair, there a variables that can make the repair more or less than the suggested time. For the 3140, there are no times listed, but from my past experience, I would expect somewhere in the 25 to 30 hour range. But as I said there are always variables. If it has a loader and mounting frames that need removing, that will add time. If tractor has been used in chemicals and all the bolts are badly rusted and twist off, that can mean more time. In our shop, if we run into problems that wil prevent us from doing the job for the estimated time, we will call with updated estimate so you don't have surprises. If they can't provide adequate reason for going over the estimated price, I would ask them serious questions. Parts used to repair can vary alot also. You can't accurately predict what parts need replacing until it is torn down.