I do not know about converting a 4 speed to a 5 speed. My grandpa
converted his 1986 Toyota auto to a 5 speed and couldn't be happier.
His mileage jumped from around 12-13 to 16-18mpg. I know when he had
it converted they used a 5 speed trany from a early 90's regular
pick-up. The had to modify the drive train length, but otherwise it
was not to difficult.
My dad owns a 1978 Toyota 17ft. 4 speed which is pretty basic on the
inside. It funs great with plenty of low end power but on vacation I
would get between 18-20mpg with my 5 speed fuel injected four carry a
loaded 21ft and he would get 16-18mpg. It seems the 4 speed is geared
to go between 35-45mph, going down moutain roads I would gain ground
on him coasting in 5th or 4th gear. Dad always complains about
needing one more gear. He always gets his best mileage cruising
through Yellowstone Park, but last year I beat him, he got around
22mpg, but I got 27mpg.
We always say that campers were made to cruise in, not race in. Most
campers will beat us up a hill but we enjoy the scenery and get even
at the gas pumps. Nate
