The 9004 HD kit will allow you to convert your dock into a rolling dock.
Here is what it contains:
-2x Heavy Duty Wheels (9001);
-2x T-brackets (9004);
-2x PVC spacers (9007-12 and 9007-34);
-2x Pins (1136).
***Axle not included***
You will need 1-5/8" diameter side pipes.
For the axle, you will need a 1-7/8'' diameter pipe.
(Calculate 2 feet more, 1 foot per wheel, for the length)