Responder a: Replacing HD portion of Fusion Drive with SSDHey Dan, how do you know what PCIe Lane model you have? I have the 5K Late 2015 27" iMac 3.2 i5 with the 24GB Fusion Drive. I bought this about 10 months ago and thought I was getting 128GB Otherwise, I would got the 2TB one. I think I'm willing to pay for it within reason, but how do I purchase one? Thanks. I been reading your posts and the info you have is very informative.