Chevrolet: no go, chevy v6, coolant system

Question
I just was given a small winniabego LeSharo motor home that has been changed to a chevy v6 transaxle.The thing ran great but the owner got sick and it sat for three years. Now the engine is fine but nothing happens when put in gear. I was told that transaxle has a high pres. valve but if it's stuck,it should be in the open position, if anything would be too much. Not too little. Can I see anything if I pop the pan and start poking?

Answer
Woody;
Hi- well is it running ok, I would change the oil and filter  a.s.a.p.. also the fuel filter and check all other filters as when a car sits for some time critters start to make homes in air filters, under seats and even snakes will make themselves at home in there.I would also add 2 cans of dry gas to the fuel and a can of gas STP treatment. than with the oil changed add a can of s.t.p. oil treatment also flush the coolant system and add new anti freeze and check all belts and hoses and replace what ever is bad, if you do not do this you could break down on the road and than you will get towed and they will charge you a fortune just to change a hose or belt.and as far as the tranny I would drop the pan and remove all of the ATf  and the filter/screen- replace the screen but if you want to clean it off a little on the inside you can spray it with a can of starting fluid as it dries clean and it will  remove any dirt or gunk on the valve body. Than replace the filter and add new tranny fluid. it should work after that.