redhatman, the 1920 is going to be too small for a Revo. At minimum, you should be looking at the 1930. The best choice would probably be the 1940. A few have run the 1930 in trucks, but the smaller motor may run too hot, depending on how much your truck weighs.

I don't own any Lehners, but have been shopping around for one too, and the information that I've gathered has led me to the 1940/8 or 9 in the hi amp version.