Transmission in a 1990 White/GMC

by Rodgersiesta
(NS)

I was looking at an old white/GMC tandem plow truck. Truck has a 8v71 and a 6 speed I haven't seen before.

Its a 6 speed with a 3 speed shift pattern. I've been running trucks for a few years and have seen nothing like this.

Is this a synchronized transmission or no? Thanks