need help choosing transmission
 

hey guys I’m trying to figure out what transmission I want to run in my 79, right now it is a 250 with a 3 on the tree and 3.08's and it has no power off the line whatsoever, dad had mentioned going to a 4 speed with a lower first gear (not a granny gear more like a car 4 speed), but I cant decide cause I want to be able to keep the cruzing rpms good on the highway. I plan on building a 250 with like 200-225 horsepower I want to try to keep it where I could get decent mileage because when it’s done I might want to go on some cross country trips or something like that.
Here is what has been running through my mind
Either a...
leave it stock
3 speed in the floor
4 speed with 3.08's
4 speed with 3.42's
T-5 with 3.73's

But I cant figure out what I’m going to do for now so if yall could give me any input it would be well appreciated, and bring up eny transmission options ive overlooked thanks guys

Re: need help choosing transmission
 

Will you be using it to haul stuff? Will you be doing any towing? What are your plans for the interior? What tires and wheels will you be running? Do you want better mileage, quickness off the line or a compromise? What is your cruising speed?

The tree / floor question is about preference and interior design, unless you opt for more than three speeds.

If you build that horsepower in the six, it will have good torque and performance at low end rpm's. People with more knowledge than me can tell you the rpm for optimal efficiency with your engine. Once you have a target rpm for cruising, you can select your gears.

Gears can always be changed later to adjust the results. Good luck with the project.

Re: need help choosing transmission
 

The question is really what you are trying to achieve. If you want to economize just keep what you have. What is your current mpg? If you want power, I would replace it with a GM crate motor 350 and 3.42 and stick with your current transmission for simplicity. A floor shifter or automatic will require a lot of mods that won't help power or economy much. Just a different rear axle will help off the line acceleration but you will give up mpg. The more mods you do the less your return on investment - save that money for gas and keep your stock setup - buy a truck of your choice later on.

Re: need help choosing transmission
 

If it were me, I would go with a T-5 conversion and try it with the 3.08 gears. I know it's got a decent 1st gear and it might be low enough to give you more torque off the line. If not then add 3.42's or 3.73s later.

Re: need help choosing transmission
 

I second this. I would try this and see how it goes. You can always change gears down the line they are easy.

Re: need help choosing transmission
 

I Just took my T-5 '78 1/2 for it's maiden voyage on Monday...Still lots of details to finish up, but for now, it's cool to watch the asphalt roll by through the holes in the floor. The trans is out of an '83 Camaro...Tag # 1352-028, with a 2.95 1st gear.
It has 275/60/15's on the back and 3.73's...Unfortunately off the line, it still feels like a truck with a straight six. If it's any better off the line, you have to try hard to feel it....On the freeway, however...60 mph used to be 2500 rpm with my old 3ott, now 60mph is 1900 rpm....the engine actually feels a little sluggish, so I think my fwy cruise speed is going to have to go up to 70 mph like normal people. Driving it on the street is very nice now...2nd gear is very nice for low speed creeping forward in traffic...with the 3 speed, 1st was too low, 2nd was too high...

Re: need help choosing transmission
 

My truck will be used for minimal towing probly a riding mower on a 4X8 trailer at the max. I’m going to restore the interior mostly stock, ill be running 235/75/R15s with crager s/s mags, I would like to improve my mileage to an extent, id like to have a well rounded truck... right now I’m scared to pull out in front of a semi 500 yards down the road, and I don’t even think about passing. I cruse at about 65-70 max.

the plan is with this truck is to have a truck that is enjoyable to drive but economical at the same time I don’t need gobs of power or a large towing capacity that’s what my 73 duster and my 77 big 10 are for. Just something I can drive and enjoy without screaming down the highway with 4.11's or lugging down the highway with 2.73's.

And I am actually checking my mileage this week i just got tags on the truck last Thursday