So I'm in a band, and we are planning on going on the road this summer. The engine in my 79 Econoline is running really bad,(Skipping a cylinder) so I just parked it for now. The engine in the van now is a 351 windsor. Since its not in roadworthy condition, I figured now is a good time to explore my "better MPG engine" options. I'm very curious about Biodiesel. So my question is... Would a diesel engine even fit in my van, and if so could it be converted to Biodiesel? If you could include sizes of engines that would fit that would be great. I will never get rid of this van, I just want to make it more economical. Thanks!