KLR650s were converted under a Defense contract by a California company. Contract now completed/cancelled, AFAIK
Know of no aftermarket "kits" for such a conversion.
Best bet for obtaining a Diesel KLR, in my view, is: Find a government surplus remainder from the original contract.
My knowledge/analysis/speculation is now exhausted; others may know of alternatives.
“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre