The serial number is c813a02032y. I think its a GDP090 it is LP. It has a 1st gear lock up switch which is why i think it has more than 1 speed. The shift lever only goes forward and back one click so i cant choose the gear with that. In Neutral the forklift sounds fine and revs up quick like it should but once i put it in forward or reverse it dogs right down and will not rev up at all just kinda grumbles and barely moves