The .5 5 speed is closer to the .3 4 speed with many internal parts interchangable. ( the .4 is a scaled down version of the .3 4 speed)

Does it try to hit 4th at all even for a second?

This might help

http://www.electrandiagnostics.com/shops/78/article11.pdf

It speaks of a no 5 th gear but offers insight on how the system works. It applies voltage to the 5 th gear solenoid in 1 through 4 gears then drops voltage to get 5 th.