Im currently getting 12mpg out of my 3 speed automatic 5.7L v8. I have read alittle about the 700r4 but havent found one that will bolt right in to my year. I like that it is a 4 speed. But is there any transmissions out there that bolt right in that are 5 or 6 speed?

My father tells me that I can swap out the gearing in the rear end very easily and get alot better mpg. What do you think of that?

Thanks for all your help

 

You would have to rework the 700R4 by replacing the tail-shaft with one that mimics the TH350 tail shaft for it to bolt right in. The 700R4 is a bit longer than the TH350as well, but most of the time, the added length won't cause too many problems. It depends on what you have.

As far as 5 or 6 speed transmissions that will give you an over drive go... You'll be looking at more replacement/rework than you would with a 700R4 swap.

 

if you change your gears the truck will be way slower. If its stock you probably got like 308s in there as it. Which 3 speed trans do you have now? You may have to change transfercases too if you have the 400

 

I dont know ehich tranny i have. All i know is its a 3 speed and im in third gear around 35 mph. I need better milege or im gonna sell it. I was goinh to get it timed and get the carbed tuned. Get some e3 plugs and possibly headers.

How can i tell u what tranny i have? And what steps i need to do to get the 700r4 in?

 

Transmission identification is pretty easy. Look at the shape of the pan and then google 'GM Transmission Identification'. THIS PAGE is pretty informative.

As far as the 700R4 swap, the easiest thing to do is find a junked K5 that has the 700R4 in it and grab the transfer case, driveshafts, and transmission/transfer case cross-member. Then put the transmission of your choice (or grab the tranny from the junker too and have it rebuilt) and install it with those components.

 

http://chevyk5blazer.com/wb/index.php?topic=2945.0

get under your truck, look at the shape of the tranny pan, and then look at the link I posted, the shape tells you which one it is.

 

There are also many results on Google for "TH350 to 700R4 Swap" that may interest you.