There are several different spring options for the HMMWV depending on how you plan to have your truck set up.
There are also several aftermarket spring sets available. The aftermarket springs will be the ones to soften the ride more than the military ones, as a soft ride wasn't on the consideration list when designing the truck.
You'll also want to check and see whether you have the welded or cast rear spring perches, as it affects which springs you can run in the rear of the truck. Some of the MAK armored trucks got the cast perches, some still have the welded.
(I have a buddy that just received 2 M1123s that are close in serial number, but have different springs under them and different serpentine belt setups, so you don't always know what someone has just from the model)