I have a 1975 Mazda Rotary 1/4 ton pick up truck. It had a 1.3L 13B in it previously and I am currently trying to find a replacement engine. The only engines I can find are same year and everything except it is a 1.6L. I'm not sure if the 1.3L and 1.6L are interchangeable. If someone knows about old rotaries or how one would check whether they are compatible that would be great.