Good Morning Phil,
You have a nice looking and solid haube there. I will try to answer. I think your saxon looks legit, the saxon wappen looks original to the body, there are no extra holes, I presume?
The chinstrap looks repro tho, but thats nt really a big thing. The brass trimmings of yr haube are still in a very nice condition,even the rear spine is very nice, too. the helmet body looks solid and only a few crazing are obvious.
As for the markings, I cant find any markings that lead to the conclusion that its a Saxon marked haube, there were 15 saxon infantry regts. Rgts 102-108, rgts 133, 134, 139, rgts 177-182, apart from the Leib Grenadier Rgt 100 and the Leib Grenadier 101. Hence your saxon should be marked with one of those rgts, apart from the 100 and 101 that is.
And I belive " 2 B" means 2 battery or 2 Batallion of the regt. And I have no idea abt the meaning of M 02, thats something new. And it seems that there are some numbers directy above the M 02 mark and it starts with the nos 13...
But overall, your Saxon haube looks ok and legit. I wouldnt mind owning it

LoL
Btw, can you pls post some pics of the liner? Perhaps there is another theory to this?
Hope this helps,
Mush