23 spline or 21

[ezthere]

I have decided to go with the dual transfer box. It make's more sense then buying the trail tamer gears, for a little more money you get twice the control over the tranny as apposed to getting the 4.7 gear. So here is my set up right now. I have a 1985 700r4 tranny with the AA adapter bolted to an 85 4.3L V6 about 300HP . I have found a doner 1986 4runner 4cyl EFI.

Q. since the out put shafts are 21 spline. I have read on this site that the 21 spline will have to be replaced. This is costly. Is it really nessary?   

Any suggestions are welcome. Thanks Chuck

[WHITE_TRASH]

You dont have to replace the 21 spline gears to do a dual setup, its just the coupler between the 2 that you would need to have either 21 or 23 spline.  If I was gonna do this swap Id do 4.7's in the rear case that way you'd not only have a stronger input on the rear case and crawler gears to boot but youd actually be close to the same money considering you would need to buy a new input gear anyway

[ezthere]

So if I go with the dual case I have to buy  a new input gear anyway

Can I rob one out of a turbo efi Box?   Well it won't matter anywho. I doubt there are any of those on island.

But I did find a donor truck and will use the body. I am thinking of taking the gas tank out of the donor truck and adding it to the project truck. TWIN tanks 

[WHITE_TRASH]

No that not the case I did a crap job of explaining myself.  If you just want regular duals you do NOT need to change the input.  But if you want to go 23 spline in the rear case you would need to use a different COUPLER than what the standard dual kit comes with.  The price to buy either one is the same.  If you wanted to go 23 spline from the start then you would need a 23 spline input on the rear case, wich as you said is about impossible to find.  So that would mean you would need to sorce one from somewhere and it would probobly cost about the same in the end to just buy a 4.7 set in 23 spline.

[ezthere]

Ahh OK.....With the HP I am running will this 21 spline hold up.? I am not overly abusive.

Any way with the donor truck I will snag the steering box, transfer box, gas tank and add that to the project truck..

Say what can I do with the rest of the transfer case after I rob the front part. Or is it rendered useless..

[Prismo]

I am thinking of taking the gas tank out of the donor truck and adding it to the project truck. TWIN tanks 

I will be doing this on my 4-Runner. I will be putting the 2nd tank where the spare tire area used to be. I plan on using the fuel pumps in both tanks and running a switch to change them over.