The unihome has a caterpillar 3208 deisel engine and an allison automatic. The speedometer was not working when i bought the RV and the guy I bought it from said he would have it repaired, the trouble is that the guy who "looked at it"..goofed the cruise control up. It was working fine before he "worked on it"...when I looked under the RV where the speedometer/cruise control unit ties into the transmission, the two wires were connected in reverse and not even taped. I reversed them and it started working but.It does not lock at the speed by turning the "set speed" control. It will only come on by turning the resume/accelerate control, and even then it only locks on to about sixty...most of the time it continues to speed up to about 2500rpm,(per tachometer) and then cuts off. I am not a mechanic by trade but am not totally lost around engines etc. I checked the breakers in the dash and they are all in tact. This is a 1991 foretravel unihome grand villa...like nellie belle?..would appreciate any ideas.