The internals are basically the same, HSCV & ETA for both. I don't think the Z1 FR with a 20mm axle were very common, but I think I've seen a few. All Z150s had the QR20. I've got an 04 Z150 and it's quite heavy, at least a lb heavier than the Z1. I still think it's a great fork.WildJackal said:What is the difference between the 2004 Marzocchi Z1 FR and Z150 .... other than travel? Do they have the same internals? HSCV cartridge? ETA?