Prinz Eugen,
Have had another look at the pix & I'm not absolutely sure, although I've seen enough cases where numbers have been 'modified' or the original numbers sanded out & then overstamped. Size?? Would need to check, but suspect either 1/8" or 5/32". Perhaps Peter or someone with a measuring stick & a No4 T handy can tell us for sure......?
ATB