Your comment re changed layout surprised me. Since my memory may be failing I visited the mir site to see what it says about 55/3.5 MicroNikkor designs. There may well have been redesigns, but all versions were five element in four group double Gauss types.
You may have been led astray by this text (see for yourself at http://www.mir.com.my/rb/photography...5mmmicro.htm):
which is not consistent with cross-sections and text descriptions of older 55/3.5s on the site.(Compared to 5 elements in 4 groups used in last versions of Ai-Spec f/3.5 Micro-Nikkor which again different from early versions of f/3.5 lens that has a simpler 5 elements in 3 groups design)
It is also not consistent with the cross-section shown in the instruction manual for the 55/3.5 MicroNikkor-P I bought in September, 1970. I just dug it out, it is in front of me now.
Many of the facts asserted on the Internet just aren't so, alas.