Please Help ID this transmission

If it's like our dump truck only time you use the deep reduction is when you're off road and want to crawl otherwise just leave the blue button alone.

 

It's most likley a rto14615. my 88 pete had one. basicly a 15 over with deep reduction. the only time i used deep reduction was to slide my trailer tandems with a heavy load. It's great for off road and heavyhaul not so mutch for everyday otr stuff.

 

If you wanted to use deep reduction taking off: 1st-2nd-3rd then pull the button back to come out of deep reduction and go back to 2nd and shift it like a normal 10 speed from that point.

 

Eons ago a 15 speed with the deep reduction had a switch on the dash instead instead of on the shifter. The switch was similar to today's that control the power divider or to slide your fifth wheel. The 1st one I drove was in a Brockway cabover with a 238 Detroit, and you needed the bottom range to get going if you had any kind of weight on. I sure don't miss the old slow weak days!