The Stovebolt Site Forums The Shop Area Engine Shop Transmission swap- 4 spd out, 3 spd auto in, HELP!

I just got a low mile 65 suburban. I've always wanted one, and now I finally have a really nice one. Problem is, neither my wife or I care for the noisy four speed, granny low floor shifter. I would like to swap in a three speed automatic such as one that I believe was available as an option in 1966. Turbo 400, right?
Anyway, does anyone have a real good educated idea of just how difficult this swap will be? I would prefer to have a column shift, too. Like the factory did it.
I think I could get all the parts from a 66 donor truck or suburban that came equipped with that tranny.
Also, I've heard conflicting info regarding using a later 700r4 trans in a heavy vehicle like a old burb. A local tranny guy says no way, don't do it, it won't hold up. Says a turbo 400 is the ticket. Right or wrong, anyone?
Thanks for any input.

A 700R4, especially if it's a later one, post '86, will be just fine. There's thousands of them out there behind all sorts of engines. Also, the 700R4 was an option, and later std equipment in late model 'Burbs, which are much heavier than the ones from the '60s. They were also used in the lighter duty 3/4 ton pickups (my Dads '88 K2500 has one).

Hy oem4me, your right the turbo 400 was available in 66 I believe, so the swap should be fairly straight forward if you find all the parts. As to the 700R4, I don't see any reason why you couldn't use one, they used them in pickups and burbs for years, just keep it cool if your going to work it, hope it helps.

Either trans will work. Just find a newer truck with the correct column and connecting parts. Crossmember and such. It is all bolt in. Column probably needs to be a 66. I am not sure about interchanging to the later stuff.

I do want to keep it looking factory stock, so I will try to use a column from a '66. What are the advantages from one trans over the other? Thanks for your replies, keep 'em coming. The more input the better.

The TH400 is a rugged trany. It has direct drive in high gear. The 700-4R is an o-drive & will give you a great highway cruising gear. It depends on your rear end ratio which will work best.

My current rear gear is a 3.73

personally, I would prefer the 400, I have had both one in a one ton dually and one in a 91 trans am convertible...man I miss that car. But the Turbo 400 seemed pretty bullet proof to me. I tried and couldn't kill it.

I take it it is a V-8 engine.

unless you swapped out the 700R4 for a TH400 in the TA, your trans had 4 gears and was a 700R4.

Regarding which trans is better, would depend on what you are looking for. Short trips, parades and minimal usage, I would stick with the original 3 speed non overdrives such as the TH350 or TH400. For any amount of driving, distance, etc. look into an OD trans. The 700R4 is a TH350 derivative with 4 gears (last being OD). This trans became the 4L60 and then the 4L60e. If you want the prodigen of the TH400, look into a 4L80e found behind BBC's from early 90's onward. Any of the E trans will need a controller, the 700R4 needs a vacuum switch and a brake switch to go into overdrive.

the 700r4 is agood trans, but any towing with it in o.d. is hard on the tranny, something about less revolutions of internal parts like the pump = less lubrication,the o.d. is nice for gas mileage. 12 versus 16 mpg

That is true, don't tow in overdrive. When the early 700s are run in overdrive, the line pressure actually drops. Towing will cause the clutches to slip since there is less pressure to hold them locked. The later 4L60E trans with the Tow/Haul switch actually regulates the pressure electronically, and raises the line pressure for towing in overdrive.
One more note about the 700R4 over the TH400, the 700 has a deeper first gear, which is better for takeoff.

Thanks for all your responses so far. Yes, it's got a 283 V-8. As for my intended usage... I am not going to beat the pants off this vintage wagon, but I do plan to do some traveling and occasionally pulling a small vintage wooden powerboat. I know wood boats are heavy, but this little thing is only 12' long.
The four speed w/OD sounds great for highway cruising and economy, but not so great if towing will fry the trans. So can I just tow in 3rd? Is that gear 1:1 ?

The four speed w/OD sounds great for highway cruising and economy, but not so great if towing will fry the trans. So can I just tow in 3rd? Is that gear 1:1 ? [/quote]

Exactly. You can tow in the 3rd gear position & it is still 1-1.