Transmission and Transfer case questions?

[donelan07]

Im looking at a 1968 pickup with a V8 its 4x4 and has a 4 speed. Is there any automatic transmissions that could be swapt with the manual transmission? Im guessing the pickup has a 307 or 327...

[1969k10stepside]

Not to the existing transfer case,and if you could,which you might,it will require a very expensive adapter.But I dont think there is one.It should still have the rockwell T 221 t case.A possible upgrade would be a NP205 T case,which is a nice,strong gear driven t case,or a NP 203 t case.The 203 is for a full time 4wd but it can be converted with a kit,the 205 is already set up for lock outs.You could also use a NP208,but I dont like them.Keep in mind you will need a different front driveshaft for any t case you switch to

[donelan07]

What transmission should I look for then? I would like to have the option of burning E85 here in South Dakota too. I thought it would be better to try to keep it original but should I just go with a newer motor transmission and transfer case? Where should I find a used NP205 T and what transmission would it go with?

[1969k10stepside]

You could convert to ethanol and it is a wise decision with the current price of gas.As for the motor part,I cant help you.You could put in a newer type drivetrain but I believe the new models have the driveshaft for the front end for the IFS on the other side.So,you would need to put in a Ford Axle to accomodate.You could use a TH350 or a TH 400 4wd Tranny.A TH350 is more common,cheaper,and easier to find.The off roaders like to use the TH 400 in their trucks as they are heavier duty.It depends on what you want to do with the truck.Just a cruiser and driver a TH350 would work.A mild off roader,tow a trailer,ect you might consider the TH400.A NP205 came on both in some cases.Most TH350/NP205 combos came in the 70-72 trucks/burbs and 71-72 Blazers.Some newer models had the 205,but very few behind autos.The TH400/NP205 combos came in the 1 ton 4wd (76?-90?) in most cases.They might have had a few in 3/4 tons too.Sometimes 205s and 4wd TH350 and TH400s show up here for sale.The TH400s,and NP205s arent cheap though,be sure to get the correct adapter plate too.Some need repair though...A used adapter costs around $150-225.

[gator2511]

Go to Advance adapter.com and check out the availability of adapters for your use. Give them a call and tell them what you want to do, I found them to be very helpful. I have a np205 tc in my truck and it has had a manual, th350 and now a th400 tranny in it. You just need the right adapter for it. You also may have to move the tc and cross brace and play with the drive shafts. Tell them what kind of engine and tc you have and they can tell you what you can use. They aren't cheap but even if you don't buy from them you will find out what works.

[byrdman]

Watch Craigslist for trannys/transfer cases. Another thing to consider is transmission output and transfer case input shafts if you start getting parts from different years. The older stuff was 10 spline then switched to a 32 with some 27's in there somewhere. To my understanding most of the parts are available to change input/output shafts but the costs for new shafts start adding up not to mention having to tear into the tranny or transfer case. The big one to remember is that the 10 spline input shaft np205 will require machining for the larger bearing that the 32 spline input shaft requires.
I have no first hand experience with any of this but have been looking to swap my TH350 for a SM465 so I've been doing a little reading.

[1969k10stepside]

and since he brought it up....
205 Input Trans
10 spline male SM465 4 speed
27 spline male TH350 Auto
32 spline female, (short) TH400
32 spline female, (long) Later model 4 speed? (Not sure if these are still the SM465 and the "long" female input may have also been behind some TH400 transmissions? Not to familiar with the "long" input.

Here's some more;
the 10 spline and 27 spline male input 205's use a smaller input bearing than the 32 spline female input.
So, for example, if you were going to run a 4 speed, (10 spline), or a TH350 trans, (27 spline), the 32 spline input 205 cannot be used. You can't change the input to the smaller bearing inputs because the hole in the case for the bearing is to big.
Now on the other hand, if you were to go the other way around, you can always have the smaller bearing hole machined out to fit the larger input bearing.

[donelan07]

So whats the best transmission for gas mileage? Does the TH350 have overdrive? There isn't any automatic transmissions I can bolt right to a 327?

[1969k10stepside]

Dont really know gas mileage wise.The th 350 doesnt have overdrive.The TH350/400s will bolt on to your 327.Its the tranny and transfer case bolting together is what you need to worry about

[71swb4x4]

If you want overdrive you can do a 700r4 tranny with the advance adapters output shaft, and a 27-spline 205 tranfer case.

[eedgell]

For gas mileage, and strength stay with the 4 speed. More power to run the automatic. Plus you already have the 4 speed, no extra $$$ spent.

eedgell

[Americanrider]

Just look for any 73-87 4x4's with a 4 sp/205 set up. They go pretty cheap around here since they rust out fast.

[mrein3]

If it was me I would (and did) switch to a th350 and NP205. Find a donor and take everything. Tranny, adapter, transfer case, front and rear drive shafts. Snag the tranny linkage and you should be good to go.

Make sure you grab the t-case shifter and bolt too. There are some differences in NP205's.

Contrary to popular belief, ALL 4x4s have an "adapter". That is the piece that couples the tranny to the t-case. Companies like Advanced Adapter make different pieces to make transmissions and transfer cases work together that never worked together before.

For mileage I would snag all the stuff above I listed then find a 700r4. The 700r4 with an Advanced Adapters output shaft will work with the th350's adapter and t-case. You should get approximately 30% better mileage with the 700r4 over the th350.

FWIW, my 4x4 with a 383 and th350 gets 9.5 mpg average. I've seen as high as 13. With a 700r4 that would be 13-16mpg or so.

[special-K]

Find a junked out Blazer and rob the 700r4 and NP208 and whatever else you need from it.It`s best to get a donor and have the complete package,IMHO.