I hope this helps as I was doing some research on the Red Dragon pumps. Here is a cut and paste from another reef forum...
"The Laguna Max Flo 1500 is the same motor block as the RD 1500. You do get a longer power cable though. The other difference is that the RD has the base plate with the rubber feet which you either need to carefully remove from the RD and glue onto the Laguna or So cal tropical reef outlet has a base they sell for the Laguna pump which should work in conjunction with the Alpha. Once you get the pump, you transfer the impeller housing and impeller onto the Laguna and you are set.
I recently purchased a Max-Flo 1500 just so I have a spare pump. You take apart the pond pump assembly and inside is the pump motor."
And here is a link to the thread...
http://www.reefcentral.com/forums/sh....php?t=2325185
Here is a link to just the motor block...
http://www.lagunaponds.com/en_us/lag...pproved-pt715/
Does it compare to your Red Dragon? I would want to look at the spec's on both pumps to make sure that they compare.
Cheers,
Norman