Pumping saltwater through a Softub motor: how bad is it?

[porkandbeans]

I don't read much about pools and spas, but I have heard several times that you only run saltwater through proper saltwater equipment. How about a Softub? Are all of the internals plastic?
Hear's the background: I might be getting rid of my working Softub. I have a crazy idea of using the motor pack to partially heat my above ground pool. I will take care of the layout, routing, and connections. The pool is seasonal and only up 3-4 months per year.
So, what will possibly occur if I were to run saltwater through the Softub motor pack? What's inside these motor packs?

 

[Isaac-1]

I am not sure, but I have read that Softtubs do not have a true heater, instead the depend on the friction heat from the jet pump to heat the water, if so I doubt you would get very economic heating for your pool.

 

[porkandbeans]

That is true and the beauty of the set up. My Softub maintains its 100 degree temperature by automatically running a few hours a day. This adds about $5 per month to my electricity bill. For over 2 years, no one has been is the tub, and all the while it has maintained the preset 100 degree temp constantly.
During the summer, my unheated pool is around 80-84 degrees. (I know - many will say that is plenty warm enough) It's not that I need to really crank the heat, but I figure if I run the very mild and slow pump/heater on a timer as needed, I can maintain 84-86. The tub is 280 gallons and the pool is 5k. The temp increase may be very small, but just a little bit would be ideal in my case. Keep in mind that I have the tub motor and would be tub may be l oosing its real estate anyways so there is no money loss to the experiment (except for tube and fittings).
Softub spas are very unique set ups in regards to design and efficiency. I'm hoping that someone familiar with Softubs can shed some light on the guts on the unit. Is there much to corrode from saltwater on the inside?