We all think of the ubiquitous small-block Chevy- or maybe its Ford counterpart- when we think of automotive engines that stay in front-line service for decade after decade, but plenty of other engines have achieved similar workhorse status. Today, we honor one such engine, the incredible Toyota R series. The R, in one form or another, was used in vehicles during five decades. You could get one with pushrods. You could get one with one or two overhead cams. You could get displacements ranging from 1.4 to 2.4 liters. And, of course, they're damn near impossible to kill. Good job, R! [Wikipedia]