tator62

I have a 71 cutlass 442 with a stock 455 and a th400 trans. Im running 3:73 gears and looking to install an over drive, I’m looking for advice on which one is best? 700 r4, or maybe a gear venders over/under unit? Thanks

droldsmorland

Gear Vendors
https://www.gearvendors.com/index.html

Olds64

I've heard folks speak highly of the 2004R. You wouldn't need an adapter plate since they were available in the BOP bell housing pattern. It would have to be built though to live behind a 455.

66_Jetstar

Either the GV overdrive unit or the 4l80E. Skip the 2004r and save the aggravation.

droldsmorland

If you disassembled a 200 and a 400 and laid them side by side you'd see the difference, A 200s guts are puny compared to a 400 or 4L80.
A GV OD lets you retain your TH400 and you get 6 forward speeds(1st, 1.5, 2nd 2.5 3rd 3.5) GVs are good to 1000HP..

Rallye469

I've had a gear vendor for years.
Held up very well behind a TH400 in the black car in my signature.
The one thing that I never liked was their electric control unit. After mounting in in 3 different places I removed it and just use it in manual mode.

Took it out of the race car and it will now be in my 65.
You'll need a new driveshaft, but other than that it's pretty easy.

Olds64

I'll say that the TH400 is probably the best automatic transmission hands down. I've had less trouble out of the TH400 in my 71 Oldsmobile that's 15 years older than the C6 in my Ford truck. If you can foot the bill for a GV unit, that's probably the best bet.

Funkwagon455

Subscribing…. I recently purchased an ‘84 Hurst 200-4r with intention to build for my 455 wagon. I am looking for the best longevity/reliability combined with the best possible economy combination. (Who isn’t right?!). While I love the bell continuity and similar length as well as lightweight, I’m also a huge fan of the bulletproof/proven 400 and am reluctant to switch. If it were not for my wife, I’d be vesting into a manual 5 speed, but alas I scared her with my G body/TKO conversion, but I digress. If the gearvendors unit is reliable, does not require tunnel mods and is validated by scrupulous drag racers on this site, perhaps I need to give the time to investigate and reconsider my direction. Thank y’all for your initial inquiry and especially the first hand experience of owner/operators. Your feedback and comments are priceless to those of us broke enough to learn vicariously.😄

Bubba68CS

Magnum 6-speed. But if you're sticking with an automatic, I'd go TH400 and Gear Vendors. I've done the built 200-4R route and absolutely hated them (tried twice). The 700-R4/4L60E is worse. The only automatic I've ever been happy with is a TH400 and the Gear Vendors units are bulletproof, so that's really the only option I'd go with if I wanted an automatic.

Lonnies Performance

I would do the 4L80E. You get the TH400 strength, the added benefit of a lockup converter & control integrated into 1 unit.
Having a high stall converter for performance & lockup for cruising is the best of both worlds.

It is not the lowest cost option, but the most tuneable combination.

I recently did this build with a trans brake & a triple disc lockup 3500 stall converter lo allow full throttle lockup on the top end as well as normal driving.

fleming442

A lot of the drag and drive superstars are running GV units, and they are putting 3-4000hp through them on a regular basis. They seem to be semi-reliable at that level, but you do see some breakage.
As far as being a bolt in and go piece, I wouldn't be so quick to make that assumption. I'm pretty sure the rear seat brace needs to be modified.
That being said, I'd probably still get one, if you already have a built TH400. If you're replacing the trans, I'd try for the 4L80E.

66_Jetstar

On paper the 2004r is a good choice. In practice its a kin to slamming your dick in a revolving door.

matt69olds

I have a gear vender in my car. I did the swap 15 years ago, when the 4L80 stuff was much more expensive. If I was looking for overdrive today, I’d go 4L80 without a doubt.

While the GV works well, I’d prefer to have the lockup and ability to precisely control shift points. The GV will require some floorboard modifications (no cutting needed) just as will the 4L80.

Find a good used 4L80, install a mild shift kit, and you will be well under the cost of a gear vender or the other overdrives.

Funkwagon455

Thanks Matt, First hand experience and foresight of “If I had to do it all over today”.

Battenrunner

How well does a 4L80 fit in the stock trans tunnel and rear mount on a 1971 Cutlass?

What is the output shaft angle if you can get it in the stock tunnel?



I know our 67 Cutlass took tunnel mods to even fit a 400 and get a decent angle at the back of the trans. It would take even more mods to squeeze a 4L80 in for us and keep a decent angle.

Because our driveshaft tunnel was also closing down quick, it made a gear vendors not feasible for us as well, as that was on my list also.

We live with 3.73 gears and a 275/60 tire (28.3 inches high) and an efficient 8 inch converter on the street; not bad for us, but I won’t be planning any cross-country trips most likely.

One day, I plan on making more power and I could use less gear.

joe_padavano

Define "best". Easiest to install? Least expensive? Largest OD ratio drop? Strongest?

joe_padavano

Actually better than you might think, and better than a 700R4.

https://www.hemmings.com/stories/art...let-chevelle-2

Battenrunner

These A-body cars want a -1 or -2 pinion angle for the 4 link minimal pinion rise under axle wrap and traction, at least for street/strip applications; which means the trans needs to be +1 or +2 at the tail