Just to be clear, these are the sizes I the leading axle, drum brake Yamaha forks:
DT175N+ = 35mm forks.
XT250K = 35mm forks.
YZ125D, E, F = 36mm forks.
IT125 = 36mm forks.
IT175D, E, F, G, H = 36mm forks.
YZ125G, H, J, K = 38mm forks.
YZ250+ D, E, F, G = 38mm forks.
IT175J, K = 38mm forks.
IT250/465 H, J = 38mm forks.
YZ125L = 43mm forks.
YZ250/465/490 H, J, K, L = 43mm forks.
IT200L, N = 43mm forks.
IT250/490 K, L, N = 43mm forks.
TT600 K, L = 43mm forks.
I can't remember when the IT250/400/425 and YZ100 each went to 38mm forks, so there's gaps there...