Changing the rear end of t600

what is it that you dont like about the 325's--should be good rearends for fuel mileage
all i have ever driven is mainly 370's
was kinda wondering if maybe a 13 speed would work better with a high geared rear end like you have

 

If the 10 spd is a direct not an OD then you really need to keep them 325's just to keep your rpm's lower.

 

thats why i was kinda thinking a 13--with those rears it take awhile to get up and running at speed wouldnt it? and the split would keep your rpms up so you wouldnt have a big drop at shift point which would seem worse with a high rear end
or maybe i just havnt had enough coffee yet

 

Swapping trannys aint the answer. A 13 speed has the same top gear ratio and actually has a higher low hole than a 10 speed. Im sure even with 3.25s its a 10 over. The whole gear it high run it slow for fuel economy thing is BS! With my current truck running anything under 64 mph it gets better fuel milage half a gear down. If you lug em they burn fuel. You need to keep em in their free running range. Usually a few hundred RPMs above peek torque. Your C-15 cat makes peak tq at around 1250 Rpms. If you run it a 1450 it will pull better and get better fuel economy. Go with the 3.55s if you have low pro 22.5s. if your tires are bigger than that then I would want even lower. Price wise $3500 for the front rear and $2500 for the rear rear. Just a bll park figure.

 

i think it is the rpm drop that he doesnt like and a 13 would get rid of that- idont mind tens on the flat--and light--but when get heavy and in the rocks--they are a bit miserable and sometimes the only way to keep the truck in its happy spot is to be able to split a gear

 

I have been talking with Inland Truck Parts in kansas city mo about re-gear my truck from 3.55 to 2.64.
They quoted 1800.00 front, 1200.00 rear re geared and rebuilt if i brought them in.
3.55 use a different ring gear carrier than 2.64s which pushed the cost up.
The carriers split 3.25 and up so you can go 3.55,3.70 or 3.90 with out much problems.
I've been quoted 12 shop hours for R/R here in the kansas city area.

 

I know this is a old thread but if you still want 3.55's I'll trade you even up and split the labor 50/50.