Gear Vendor

[Shifty]

Anyone use one on a 4x4?

[JohnnyPopper]

Well, there are plenty of folks who have, I'm not one of them BUT...

To get the information you seek about your own truck, where members can assist you, please include the make, model, engine size, transfer case model, gear ratio of your existing drive train as a starter.

Without that, we are limited to offer any meaningful commentary. 

[Shifty]

1987 V20 350/TH400/NP208, but unsure of gear ratio, if I had to guess, it feels like 4.10.

[zieg85]

I've done some research and for what you gain isn't worth the cost to do it, having the front drive shaft lengthened and the rear shortened.  It takes a 4.10 and makes it a 3.28 final lowering the RPM by 20%.  ROI is hard to justify unless it is a daily and maybe 2 mph gain is worth it.

[JohnnyPopper]

Their factory is down the street from my office, dropped looking for costs on  my K10,

pretty spendy, like 3500 plus labor.

You can buy alot of gas for 5k.

Ever thought about replacing your TH400 with an OD trans?

[Shifty]

It's not mileage as much as it is being able to get on the freeway without my engine screaming in agony.   


I'd like to go 4L80 though (I just had the TH400 rebuilt....grrrr.....).

What will be needed with the 208 transfer case?

[JohnnyPopper]

I'm not familiar with that unit, but do know that your replacement trans has to come out of  a 4x4 due to the tail stock.

I looked into replacing mine with a 700r (sic) it would have been a used one with a warranty, installed at 1K.

Not clear on your engine screaming...I think it's due to your 4:10 gears.

Going with a OD, I don't think that's going to stop because gears 1-3 are pretty much the same.

So I see where you would use the Gear vendors to change your overall gear ratio.

[Shifty]

Yeah, I can't even get on the interstate, Big Blue can only manage about 65mph, and it's really spinning the engine to do that much.  55 feels more like the maximum, and I'd get killed going that slow.   

[zieg85]

Is the sticker still in your glove box with all the codes on it?

[JohnnyPopper]

I take back what I said about the OD. It will be the best thing you can do!

I think it will drop your rpm by 6-800? giving you alot more head room.

Will some Tranny head please step in and give this guy a hand? 

[Shifty]

Is the sticker still in your glove box with all the codes on it?

Possibly...I'll look tonight, assuming I remember....

[Irish_Alley]

Lift kit and bigger tires   . I know on my 79 with 38s the fastest she would go was a between 70 and 80. But it was stupid to drive that thing that fast without upgraded brakes and those huge tires. Think my Cummins doesn't go that fast either both have 4.10 and the Cummins has an OD trans.
If I'm going to do anything in my Cummins it would be to lower the ratio to something around 3.55 like Dodge does. If you're not going to really tow I would think about changing gears also but as you probably know you have to change the front also

[JohnnyPopper]

I thought the same thing Irish, changing the gearing front and back might be less work than finding a suitable OD, and having to move any cross members and and shifting levers.

[Shifty]

I've thought about that too Irish, but I really like the numerically higher gear for daily-driver duty.

[JohnnyPopper]

Numerically higher means higher engine RPM, which is what causes the 'screaming'.

If you want to keep it, Your best bet is changing to a OD.