Gear Question

[CRASHJT]

Hello I was kinda curious what gears people were running I have a 69 250 with the 3 speed and the 300 engine going to a D60 with 4.10's and cruising I can run at 60 but the truck likes say 45-50 alot better I was wanting to change the gears in the rear but Im unsure what to go with I still have and plan on keeping the non power drum brakes all the way around so Im not wanting to do 100 cause lets face it....It wont stop but being able to cruise at say 65 70 would be great and would definitely help my MPG any numbers or ideas will be appreciated

[Wes]

there are many gear calculators out there. I not sure what the cruising rpm of 300 six is, or your tire size but try this link
http://free.grisoft.com/ww.homepage-appf8

[CRASHJT]

Yeah thats my problem I dont know what the best rpm is, I dont have a tach and I have yet to find a gear calulator with an option for the 3 speed trans

[AlleyCat]

To get an idea of what RPM works best you could hook up a test tach and go for a ride.Since the leads on most test equipment are too short to reach the cab you can stick it under a wiper to hold it down.Just be careful not to crush the wires when closing the hood.

On the gear calculator you can use a non overdrive 4 speed for calculations.Both your 3 speed and a non o/d 4 speed will be 1 to 1 ratio in high gear.

[CRASHJT]

Thanks that helps the biggest hold up was the trans issue

[FLATBEDFORD]

I had an '83 F250 with the 300 six and Dana 60. It had 3.55 gears, and 33x12 tires. What ever that works out too seemed to be pretty good with the 4 spd. It sounded pretty happy at about 65 mph and I could get as much as 18 mpg on the highway.

[clemm17]

Max rpm is going to come in 32 to 3500 rpm. there are alot of variables like exactly what cam it has.
I have run 300 sixs alot and I am currently throwing away a 390 to replace it with a very custom built 300.
With a 7:50 X16 tire, 3.73 gears would give you a good blend of power and fuel milage. Another option is to leave the 4.10 gears and replace them with a taller tire. 9.00X16 works very well! The 3 speed might be a factor, I have never run a 3 speed.

[FLATBEDFORD]

I would think that you go with much taller tires, you'd wish you had the creeper first gear of the 4 spd.

[CRASHJT]

Yeah Im not really much of a 3spd fan either however my truck is so clean and stock I was wanting to keep this one all Orig. and only change the gear in the rear however I dont want to change it so much that I lose the abillity to tow anything???? I just cant make up my damn mind....