When I bought this, I could not find a complete unit for the passenger door anywhere. Not on here, not on the internet. I don't know why, but I just couldn't find one. Being the window had to be repaired and this was OEM, I gave it a shot. Assembling this is a nightmare. One of the wheels on my old track was damaged so I had to try and fix it as best as possible because you have to reuse the old tracks. With the unit fully compressed, it is damn near impossible to get everything where it belongs. Just before you get the last thing in place, it tends to slip and the whole thing comes unwound which is a nightmare to get back correctly. You really need multiple hands to do this job. After 2 hours of trying to assemble this thing, it was finally together and works fine. Well, at least for now unless that track wheel comes back to haunt me. I would HIGHLY recommend you buy the complete unit. It is worth every penny to not have to deal with assembling this.