what all is needed to convert a farmer 4spd to an auto
 

a friend of my dads has a 71 gmc shortfleet 4x4 with a farmer 4 spd and he wants to convert to an automatic...the truck has a 327 in it, he isnt too famillair with these years of trucks so i said id find out all the stuff he needs to do the swap, so far on my list ive came up with :

1. th350
2.auto crossmember
3.tranny linkage
4.automatic steering coloum.


what else is in there...will an auto tranny bolt up to his transfer case? what about a different driveshaft? any help would be great asap!! thanks guys

DEREK

Theres a thread posted on the 67-72 Parts Board under F/S Parts by Burnsman, he has a manual to auto swap kit listed for $100. I don't know if it's everything you need off the top of my head, but it's probably a good start. Good luck!

Derek,

the 4 spd transmission has a 10 spline output shaft, and the 4 spd NP205 transfer case has a 10 spline input...autos have something like a 27 spline rear output and the auto NP205 has a 27 spline input. sooo...he will either need a transfer case from an auto truck, or he could convert his existing NP205 to 27 spline with the input shaft from an auto NP205. you will need to find a TH350 to NP205 adaptor from another truck, which may be hard to find...GM sells them new, but they are expen$ive as hell. probably the easiest way to do it would be to find a complete TH350/adaptor/NP205 and go from there.

he may or may not need driveshaft mods...I am not sure on this one.

hth

Thanks adam

Re: what all is needed to convert a farmer 4spd to an auto
 

Derek
On 4x4s the automatic crossmember is the same as the manual. GM made it so the adapter bolts to the crossmember. All differences between the tranny/transfer case combos are made up in the adapter.
Like 1969 GMC said, get a complete th350/np205 and go from there.
The adapter is usually cracked. I've never seen or heard of a used one what wasn't.
Inside the adapter is the "drive sleeve". The sleeve couples the output of the tranny to the input of the transfer case. I'd get a new one of those. They are available at the dealer for around $100. New adapters are around $200. At least that was the prices when I did the swap. If you don't get a new adapter replace the oil seals on your used one. The seals in the adapter keep the tranny fluid in the tranny and the gear oil in the transfer case.

The driveshafts are the same.

Don't forget you'll need lines to cool the transmission fluid (and heat it in the winter). I think I paid about $30 from in-line tube. Of course you'll need a radiator with the coolant tank in it. My radiator already had one so I just bought a can of flush from NAPA and blasted the crud out of it.
And like you figured you'll need the automatic steering column and the linkage between it and the transmission.

One more thing - you need a kick-down cable bracket for the top of the intake manifold. My truck currently has a 2bbl. carb. I used the kick-down cable bracket off a 1971 Monte Carlo that had a 2bbl and a th350. All the kick-down cables are the same. I'm pretty sure the brackets are differnt on a 4bbl. verses a 2bbl. Edlebrock makes an aftermarket adjustable one if you can't find a stock one.

mrein3- thanks a lot for all that great information

Mrein3, why are you running a 2 barrel? Do you get a mileage benefit from it? What kind of mileage do you get. What kind of power compromise do you think it causes?

Before I swapped my 3-speed manual out I was getting around 10mpg. 9 pulling the boat.
After I get about 9.5. 9 pulling the boat.

The ONLY reason I run a 2bbl is because that is what was on the truck when I bought it.
I have a BRAND NEW in the box Edlebrock 1406 ready to bolt on. I painted a stock 4bbl manifold this spring. Got the stock air cleaner on the shelf. I got everything I need to put it on except the time.

Some of the old timers I deal with claim I'll get better mileage with the 4bbl if I keep my foot out of it. We'll see.

I wanted the new carb more for the fact that the 2bbl I got on there now runs like crap and I can't get carbs to work good after I "rebuild" them. Everybody on this board says the 1406 is the way to go. I'm sure the power compromise is huge.

Good Stuff, Thanks

Try this: http://67-72chevytrucks.com/vboard/s...threadid=33266