Overdrive or Gears

[edman87]

Are you wanting for gas mileage or engine longevity?
If only for mileage reasons, I say deal with the expensive fillups. You aren't going to make it much better.

[75sierraclassic]

Originally Posted by edman87

Are you wanting for gas mileage or engine longevity?
If only for mileage reasons, I say deal with the expensive fillups. You aren't going to make it much better.

Edman 87 has a point.
If you assume 10000 miles/year driven, and gas stays at a constant $2.50 (I know, constant gas prices ha ha ha). I'd assume you may get an average of 12 MPG with your current setup. I would also guess that the overdrive will only gain you a lot of mileage if you drive at highway speeds most of the time, but lets assume it gives you 2 MPG. At that mileage (14 MPG), gas price, and miles/year, you only save $300/year.
I'm not sure how much a 4L80 or gear vendors overdrive is, but if it is $2000 then it will take a little under seven years to even break even and start saving money.
And if you are curious, yes I am bored at work

[kevinr1970]

I remember looking at a '90 or '91 1-ton 2wd crew cab dually that had a deisel a while back. It was a navy surplus truck.
It had an overdrive tranny and I was told by someone here that it was the 4l80e. He said that for that year (not sure if the deisel had anything to do with it) that they didn't use a seperate controller. He said that would be the tranny to get and rebuild if you were looking to upgrade to a 4l80e.