I have a old case 1845 gas skid loader and the engine has been slowly going to hell and the other day it finally started knocking. I can’t find a case G159 engine anywhere and I think the engine was a poor design so I was thinking of possibly trying to repower it with a 3.9l 4BT Cummins and just curious if anyone’s done this or if I’m limited to just overhauling the 159 case engine?