I ended up with this thing, it has taken some research to figure it out. From an 06 600HO RMK chassis. Polaris Race Department 726 engine with SLP 727 heads. Based on my location and the extensive mods to the sled I am pretty sure where it originally came from, but no proof. From what I can find, SLP built the Race Dept. engines with their heads. I have a complete engine that needs one piston, not sure why it had an issue yet, only have the head off. From what I understand it also runs a stock 85mm Poo piston. The cyls are good, the head inserts are good. The carbs are bored and machined. I have the ecu. SLP pipe and can. The cyls have some very pretty porting. Again, from what I can gather, extensive work to the cases was done to fit the 85mm cylinders. 64mm stroke. I would love it if someone would come get this thing and put it to good use. I don't want a lot for it.