Valv

I saw some truck that have a 2 speed selector on shifter. What's needed to install it on my truck ?

Do I have to replace the rearend ?

ckt_santiago

They make two speed splitter boxes that actually go in between your trans and your rear end... 28% reduction on the low side or 28% overdrive your choice look em up on ebay you should find en somewhere... Easiest though would be to find a 2 1/2 ton rear end from a medium duty and retrofit it under your monster. Look at the bright side of that and you'll see that you get the advantage of 19.5 or 22.5 rims and higher load rated tires

clutch1

Yeah its probably a overdrive unit. $2000 about, IIRC

Fueling around

It is probably an E-brake control switch. That make mounting kits and it is popular with the hand shaker crowd.

blackdiesel

yeah, my exhaust brake is setup to a two speed rear end switch on the shifter

Harold Swanson

I have a 2spd aux trans on mine,its made by us gear and cost 2300 .