Later-model transmissions like the SM-318 have a drift pin that intersects a slot in the reverse idler shaft from the outside of the case. The shaft is removed by tapping the pin into the recess in the shaft, and the pin is short enough to fall all the way into the recess. It's VERY difficult to see the pin, as it's usually driven flush with the surface of the case. Do a thorough cleaning with a wire brush and solvent or you might miss it. (Assuming the older trans retains the pivot pin the same way)
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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