gear ratios in direct drive vs overdrive

I have the same set up, just with a direct 10sp. There is a 13sp, single over, has an actually slightly lower 1st gear and 12 is direct, 13 being od. I was thinking of doing that and keep my 2.67's

 

RTO has OD in the back box

 

Their is also an RTLC which is a convertible 9 to 13 that ends in direct that may be worth looking into for the guys that buy a truck with really tall rears

 

actually said to myself after I posted there’s probably a few odd balls out there too with different ratios as well, just less common

 

Swift made those convertible ones popular. They’d run their FLD’s as a 9 and then SelcTrucks would convert them to a 13 before they sold them.

 

A lot of times to they just order the 13 and change the shift knob

 

I put in 3.07 last year with a modern 13 speed. I absolutely love the combination for general flatbed freight. Would be even better with a van or refer. I usually run about %30 empty at 70 to 80 mph.

I wouldn’t want to do ag, construction or local work with it though. It struggles on soft ground in 1st gear. Low is ok though. Once rolling it’s fine.
My fuel economy hasn’t changed but I’m probably running 10 mph faster than I was with 3.73 and 10 speed.