This may be a dumb question, but where did the 90VAC rating come from? Seems a rather odd operating voltage? As for a replacement DC motor, the package you have there is a common DC motor package for actuators, but you woould need to match the worm gear on the shaft.
Waht is it you are operating with the actuator? There may be a better way, using a different device, since my experience with that type of actuator has shown some problems. One of the draw-backs is that they are often easy to "back drive" under load, that is they will screw backwards and retract with a load if there is no mechanical braking. Acme screws will not do this.
Perhaps you have a universal type motor, and the original design used AC.