15 speed Eaton??

The “Cheater”.....

 

Both 15’s....

 

I believe this should clear everything up.
Shift Pattern From The Original Fast N Furious

 

I'm pretty sure I would grind a gear or 12 the first few times driving the 15 with 4th on the bottom and 5th on top. That would definitely take some getting used to

 

Direct 15 spd, OD 15 spd.

 

The gears on a 13 speed are low and 1-4 in low range then 5-8, which are split. Low is not used in the high range, and the splits are not h and l, they are direct and OD. The gear you think he skipped isn't in a 13 speed, except as the cheater gear.