I asked them if they were heavy duty springs and they said dobinsons only make one type that is different lengths to suit the need of the vehicle.
Do you know what the part number is on your coils? The dobinson Heavy Duty coils are the same wire diameter as the medium duty coils but are longer in free height. They will keep the height with the bullbar and winch without making the ride too harsh. The coils you have now may not have "sagged" but rather compressed with the weight. Fitting the "HD" coil should sit it back up perfectly.
If anyone has a good spring that they recommend it would be great as my MTZ’s are scalloping on the front.
We have a range of coils to suit the Hilux from lowered to extra heavy duty raised applications. All of our coils come with a lifetime warranty and are $220 delivered for newhilux.net members. I'm sure we can work out the right coil for your vehicle.