There are 3 different types of 144 pistons made by Wiseco.
The 9816MO5801 is my custom piston that has been refined several times since 1991
the Wiseco catalog parts 846MO5800 and 836MO5800 are for the YZ and KTM/RM respectively. The YZ144 846 piston is the closest copy of my 9816 and interchanges. The 836 has a timing height 1mm greater, is flat-topped, and the cam shape is designed for triple exhaust port designs, whereas my piston is for delta shaped exhaust ports. We've used my piston in the RM and KTM before Wiseco made the 836 and didn't have any problems. But Wiseco has a special shape for the triple exhausts. Once a cylinder is set-up for one or the other piston, you can't interchange them because of the difference in the timing height.