Whether it's a Dexter or any other brand that you can find in stock at a somewhat local dealer for axles or boat place or snowmobile etc dealership
take the numbers off of your current axle so they can match it up. Ale weight, length etc are important info that the axle part number will show. Also talk to your mechanic and ask him if there are any salvageable parts on your axle, such as brakes, hubs etc. If they are all ok, and the axle is just bent, ask your mechanic how much it will cost to swap them over to a new axle. I say this because axles can be bought bald, as in no hubs, bearings etc or fully assembled with hubs bearings etc. There will be a big cost difference between the two. The trick is to make sure the hubs & bearings are the same between the bent axle and the new, If the cost is essentially the same between what the cost is between a fully dressed axle and what the mechanic will charge to swap over the parts from the bent axle then go for the fully dressed axle. Then there is no issue with comparability, and save the old axle for spare parts.
Just food for thought, having been there and done that a few times. Good luck!