The Marvel-Schebler TRX was an updraft carburetor used from 1936 to 1951 on Massey-Harris, Minneapolis-Moline and Oliver tractors.
Marvel-Schebler TTX carburetors were used from 1934 to 1942 on Minneapolis-Moline and Oliver tractors.
Most TRX and TTX carburetors are marked Schebler only. Some are also marked as TR and TT, rather than TRX or TTX. The float bowl and throttle body were cast iron on all models.