May 8, 2018 / 2004 Kubota HST L5030 knock and blue smoke #21 Kyle_in_Tex Super Star Member Joined Oct 24, 2002 Messages 12,680 Location East Central, Texas Tractor JD 4310,JD5420 Modify it and put a Duramax in it. I'd be looking hard for a used engine or another used 5030.