The easiest way to understand a Lenco is that they are a series of manually operated two speed automatic transmissions stacked one behind the other. As I recall, the original ones used Buick Dynaflow clutch frictions and plates that were forced together by a ramp affair that pushed the clutch pack together to engage the gear reduction. When the clutch pack is released, the planetary disengages and the unit goes to a straight thru 1 to 1. Supposedly you can downshift a Lenco, but not under power. I would contact Lenco for verification to be sure on that though.
https://lencoracing.com/index.php?ro...ormation_id=17