727 guts question

I have a 76 car trans I took apart and put the guts and valve body in from a 77 Winnebago 727. The reason I did this is to have a slip yoke instead of a bolt on yoke. My question is the servo piston that is exposed when removing the valve body from the car housing there was a heavy spring pushing the piston down and nothing under the piston. The guts I used from the truck trans had nothing on top of the piston and a small spring pushing the piston toward the valve body. Which is correct??