Here's the top feed unit on my 2008 (vs. center feed - what the military calls them):
View attachment 927425
There's no notes in the TM on the start serial number. I think it was around 2006 or 2007 that these were introduced. It was later than the 100,001 start of the A1R serial numbers. Obviously all the A1P2's are built this way. It's just a center axle diff from the MTV with the output blocked off and the power divider replaced with a spool.
Off road performance with ECO hubs is basically unaffected because you can fully load the TC and get it's 1.89:1 reduction that you normally wouldn't see due to the hub reductions not loading the TC enough to get the reduction out of it. You trade the 2:1 for the 1.89:1..... which is basically a straight across trade for all intended purposes. Low speed crawling is the same and with the 290, 330, or 370 HP engines you will run out of traction before you run out of torque.
Again. EVERYONE needs to read through the entire ECO hubs thread. This is all covered in minute detail.