5 Witte Natural Gas engines for sale

[dieselfox]

Gentlemen
I came across these engines while looking for a diesel version of a Witte.  Does anyone know if these can be converted to diesel?
Diesel Fox

http://www.rotationpower.com/index.php?main_page=index&manufacturers_id=25

[LowGear]

These aren't really that much different than my BD unit of 1952.  That blue one looked interesting but I couldn't make out if it was a vertical unit. 

Thanks for the look.

Casey