What axles should I use?

[monzajhon1968]

Hi all!
I am new to DTR and there might be a thread on this allready if could help me find it or just any help would be awsome! What would be the best all around gear ratio to use in my 1986 suburban 6.5 with a banks turbo. The 6.5 is a N/A out of a bus with low miles I am going to put a banks kit on it. I have a 700r4 tranny that is going in it. Its out of a 87 6.2 4x4. I have two sets of rear end gears 4.10 and 3.73. I will be doing a little towing with this truck ie; car trailer and a 22 ft camper and possibly a enclosed car trailer 20 ft. But I will use this truck around town and a family vacation vechicle not always towing. I have a set of 265/75/16 wheels and tires and probably wont go any bigger my monster truck days are done! Any help would be appreciated I am going to build the 4x4 drivetrain first and then do the body swap later. I dont want to cripple the 2wd burb yet going to use it this summer for a vacation the 2wd has a big block with 4.10 gears I am so done with 8 mpg. BB has got to go! I am guessing the diesel will get at least 16 mpg thats double what I am getting now.
Thanks

 

[THEFERMANATOR]

3.73's would be a good all around gear, but the 700R4 stock will NOT handle a 6.5 with a turbo. They couldn't really handle a 6.2 without a turbo very well. The tranny will definately be your weak link, a 4L80E would be money ahead in the long run IMO.

 

[monzajhon1968]

I have a local tranny shop that says he can build one strong enough. I originally thought the same as you did. The only reason I am thinking of it is because I have it already. How hard would it be to put a 4l80e in how much modifications? I know they have stand alone computers for older applications. I can buy a GV overdrive and keep the turbo 400 just talking more $$$$

 

[THEFERMANATOR]

A 4L80E wouldn't be hard top put in it, the big obstacle is getting a controller to make it work. The PCS one seems to be the best for the money from what I have read. And as for the 700R4 holding up, even a built one isn't as strong as a stock 4L80E with just a shift kit in it. I built up a 350 for towing for my uncle and now he keeps eating the 4L60E, even built ones aren't holding up to just a small block chevy. A 6.5 diesel is a whole nother story.

 

[monzajhon1968]

Yeah! you are right talked to the tranny guy locally again and he said the same thing 4l80e would be the best all aruond solution now I just have to find one! He told me to get a 1994 or later core for a 4x4 hd. He wants to build it and build a converter for my application. Anyone know where I can get a good core chep?

 

[THEFERMANATOR]

A 91-93 would be best in my opinion as they have the extra tone ring already in them for the output speed sensor. The 94+ put the output speed sensor in the transfer case which causes problems with the aftermarket tranny controllers. Your builder could add the tone wheel though if he knows what he's doing. The 99+ have all of the updates in them that allows higher torque ratings.

 

[tinypeckerwood]

I think it would be less $$$$ to do the TH-400 and the GV O.D.. The 4L80E is a good trans, been told its basically a TH 400 with OD. I think the GV is like 3200 but you may be able to find a used one on the cheap.

 

[THEFERMANATOR]

Ne GV's are about $3K plus install, and used ones bring close to $2K. You can pick up a 4L80E with a torque converter for around $750 that was still good most of the time, and get a PCS controller for about a $1k. Yes the 4L80E is basically a turbo 400 with an overdrive unit added on to the back. The 4L80E has a .75:1 OD and a GV has a .79:1 overdrive to it.