Phazer and Phazer II engines share most of the same parts. There were some differences in minor components (electrical and some other) over the years but the internals are all the same. The 99-01 Phazer 500 engine is completly different. The cylinders, pistons and heads carry a different part # but I am told they would be interchangable with the early Phazer/II engines however the bottom ends are completly different. Crankcases, crankshafts, electronics, etc will not interchange.
opsled