3 speed to 4 speed...

[jmbstudios]

Right now I have a 350 trans in my 72 3/4 ton Burb. Its a 3 speed.

I was wondering how difficult it would be to put a 4 speed in it.

Will the gas mileage improve..... even a little?

Is the 4 speed better for travelling out of town, say a 3 hour drive?

And one more, where can I get one that would be best on my pocket book?

thanks

jeff

[earl87gta]

most 4 speeds have the same final gear ratio so most likly no change but you can go here to find out. http://www.grimmjeeper.com/gears.html

[jmbstudios]

Since i am clueless to the technical stuff, i guess i should take it to my mechanic and have him school me on it.

thx
jeff

[earl87gta]

If you change to a 700r4 with an over drive you will get better fuel milage it would be the easyest swap for an over drive. check out 700r4.com or botieoverdrives.com

[sweet70beast]

When you say that you have a 350 trans now I assume that the 4 speed you mean is a 700R4. A 4 speed manuel would mean you would have to much to swap over and would not be worth it (no overdrive). The 700 swap is pretty straight forward, the yoke on your driveshaft will slide right in as the 700 has the same output as a TH350. The 700 is longer than a TH350 so the driveshaft will need to be shortened and the cross member will need to be moved back, I put a 700 in a 72 GMC 3/4ton a few years ago and the holes in the frame were already there. The 350 mount will bolt to the 700 as well. The column shifter will work with it too, it will just go past the 1 when you put it in low(the shifter will go down that far).

[jmbstudios]

Good, so I will look for a 700. Maybe when I get the money out for my A/C replacement, I will get some for that too...

Any Idea of a price that I am looking at...?

thanks
JEff

[earl87gta]

depends on hourse power and if you want rebuilt or used trans used trans fromj a firebird you can do the hole swap for less then 500 for a reman trans 1000 for big hourse power 1500.

[jmbstudios]

I have the regular run of the mill 350 in the burb. Not sure of the horse power.
No mods, not original. The guy that went through it for me said there was no sludge or carbon build up in it. Said it looked extremely clean inside.

Anyway, whatever would work best for the tranny. I would like to put a good strong one in for sure........

Jeff

[earl87gta]

you can use the same cross meber you have now. the wiring kit to make the lock up cunverter is going to be 50 to 100. you can use a cable shifter around 100 or a universal shift rod kit 50 for the steering colume you have. After that its just the cost of the trans. you will have to buy or make a braket to use with the tv cable seen them sell from 10 to 50. drive shaft I think you will need to shorten around 1in or so its not varry much.