I would really like a turbo 400 in my truck

[jakewalter]

I have a 85 K20 that I built up to haul our 3500 pound pickup camper.

It currently has a pretty healthy big block that I built for torque.

The transmission is a 700R4 and a 208 transfer case.

While on vacation a couple of weeks ago the transmission started slipping and I lost reverse.

I never use the overdrive and as for mileage I threw my pencil away a long time ago.

Other than a TH400 out of a 4wd what else would I need?

I would really appreciate any input that you guys could share with me.

I need to apologize.

The guy that rebuilt my transfer case said that it is a 208 not a 203.

 

[nvrenuf]

You need a 4wd th400 from a 400/203 combo. The th400 tailshaft that fits a 203 is super short and only fits that application, nothing else 2wd or 4wd.

You will also need the trans to tcase adapter and kick down switch for the gas pedal.

 

[jakewalter]

You need a 4wd th400 from a 400/203 combo. The th400 tailshaft that fits a 203 is super short and only fits that application, nothing else 2wd or 4wd.

You will also need the trans to tcase adapter and kick down switch for the gas pedal.

I need to apologize.

The guy that rebuilt my transfer case said that it is a 208 not a 203.

 

[nvrenuf]

You’ll still need the correct tailshaft, I think it sticks out of the case 3.5” but I’m not sure. Also you’ll need the adapter.

Another hurdle will be the tcase input shaft, the th400 is 32 spline and the th350/th700 use 27 spline. I believe the 2 input shafts for the 208 are a direct swap.

 

[Old Guy Bill]

I just changed the 203 to a 208 behind my TH400.
A 6-7” tail shaft is needed, I could only find a good used one from Novak.

 

[nvrenuf]

I just changed the 203 to a 208 behind my TH400.
A 6x7” tail shaft is needed, I could only find a good used one from Novak.

Just to be clear, you are talking about total length, correct?
My estimate was just what sticks out of the case.

 

[Rusty Nail]

Just to be clear, just what sticks out of the case?

No. They speak of the whole thing.

 

[nvrenuf]

No. They speak of the whole thing.

That’s what I asked. See my post, not what you quoted.

 

[Old Guy Bill]

Middle one, bottom row.
The new ones sold by Jeggs & Summit are for drag racing and have no provision for turning the Governor.

 

[nvrenuf]

Middle one, bottom row.
The new ones sold by Jeggs & Summit are for drag racing and have no provision for turning the Governor.

Are you sure the 4.5” stick out fits a 208? I thought the stick out was less than a figure 8 205 tailshaft.

 

[jakewalter]

You need a 4wd th400 from a 400/203 combo. The th400 tailshaft that fits a 203 is super short and only fits that application, nothing else 2wd or 4wd.

You will also need the trans to tcase adapter and kick down switch for the gas pedal.

I need to apologize.

The guy that rebuilt my transfer case said that it is a 208 not a 203.