The only difference between Makita SP6000J and SP6000J1 is that the SP6000J1 comes with a 55-inch Guide Rail. The rail part number is 194368-5, commonly costs over $70. Thus, the SP6000J1 is more expensive than the SP6000J.CHECK sp6000j PRICE AT AMAZON
SP6000J or SP6000J1 which one to buy?
If the 55-inch track is too long or too short for your projects, you can buy the cheaper SP6000J, then use the savings to buy a shorter Makita 39-inch track(part number is 199140-0) or a longer 118-inch track (part number is 194367-7).
Otherwise,just purchase the SP6000J1.