Jim
The wheel hub is pretty common. HUB, REAR (483-25311-12-98) so any of the following should fit.
1974 YZ250A REAR WHEEL
1974 YZ360A REAR WHEEL
1975 MX250B FRONT WHEEL
1975 MX250B REAR WHEEL
1975 MX400B REAR WHEEL
1975 YZ250B REAR WHEEL
1975 YZ360B REAR WHEEL
1976 IT400C REAR WHEEL
1976 TT500C REAR WHEEL
1976 YZ400C REAR WHEEL YZ400C
1977 TT500D REAR WHEEL
1977 YZ250D REAR WHEEL YZ250D - E
1977 YZ400D REAR WHEEL YZ400D E
1978 TT500E REAR WHEEL
1979 IT250F REAR WHEEL
1979 IT400F REAR WHEEL
1979 TT500F REAR WHEEL
1979 YZ250F REAR WHEEL
1979 YZ400F REAR WHEEL
1980 IT250G REAR WHEEL
1980 IT425G REAR WHEEL
1980 TT500G REAR WHEEL
1981 TT500H REAR WHEEL
Peter B