2 main mods. one is for the harddrive and the other for the amd cpu.
for harddrive pretty much they are all the same for all versions.
for the amd mod, the later v4 and v5 don't require mods to run an amd at 200 mhz. just drop cpu and go. but if your dropping an amd you would want it to run faster than 200 mhz, so you would do the mod anyways.
because of the degree of difficulty in the amd mod, it wouldn't matteer which version you get. tehy're all pretty the same in soldering in tiny parts.