TMR0019 is a downflow radiator for the Mack MRU, model years 2007 to 2016.
The core measures 38.75" high by 27.5" wide, 2.25" deep. It has a 2.3125" inlet at the right and a 2.5" outlet at the right. The unit carries an oil cooler at the bottom and no filler neck.
It replaces 39 OEM and aftermarket numbers, among them MAC51F, 1003654, 1003654BS. Searching any one of them will find this part.
On radiators the inlet and outlet positions, and whether the unit carries an oil cooler, decide interchangeability more often than core size does. Two radiators with identical cores are frequently not interchangeable.