FNG/ Heads Selection Assist Needed

The st300 IIRC has the same yoke as a TH350, so you should be good there if the TH375 has the same yoke as a TH350?

Definitely do aluminum heads too, the SE Stage 2 are the way to go for the street if you are planning on headers. If you want to run manifolds then the SE Stage 1 or the BBB Edelbrock heads would be the way to go.

 

There are two entirely different "375" transmissions in the modern era.

375 is a LOW-torque, cheap version of the TH400. Scare up a couple of drums (that accept additional clutch plates), a different output shaft, and a tailhousing, and it's easily upgraded to full "400" status. I have done this--about thirty years ago. All normal TH400 service procedures and "shift kits" work with this trans.

If you wanted, you could build a medium- or high-torque "400" or even "475" internal-parts transmission, then use the smaller output shaft from the 375. It all depends on the end goals desired.

375B is a HIGH-torque version of the TH350. Additional clutches are the biggest part of that. All normal TH350 service procedures and "shift kits" should work with this trans (I have zero experience)

 

Mine looks like the 400 but smaller so i think it is the A?

 

Will i have to change the shifter on the tree?

 

count the splines on the output shaft, if 32 it's a 400 output, if 27 than not.

now there is 2 different 400 slope yoke ods. and 2 different 400 tail housing ids.

early 400 through 67 I believed use a different slope yoke and a newer one fits the splines but wont slide into the tail housing and it must be swapped with newer unit accepting the more common larger od slip yokes

 

When i looked the numbers up it showed a 375?

 

32 teeth

 

ok 32 spline is th400 outut.......I forget the od of the different slip yokes, but I'm almost 100 certain pre 67 took the smaller od.......which is just fine, if you have the yoke........if not almost every new and most used yokes fit the larger od.

it just takes a different short extension housing and the your good to go if yours is the small

 

Thank you guys. Now on a totally different note i just opened up the extra rear end it came with and found it has posi 2.73 gears. i was also given a set of 3.23 gears. Will they work or will i have to get a new carrier?

 

It is an 8.2 10 bolt, not sure what it is out of the numbers on the rear end are 1385724? Numbers on the other set of gears 1234478 and they say gmc 42 13?

 

Here's the pictures of it.

 

That is the 68-70 Buick 8.2”.
Do you have a picture of the 3:23 gears that you got with it?

 

I have had a few 375's in my life,I do have one in my driveway right now.The 350 shaft will fit into it,but the seal will not close the gap,,so you actually need a 375 yoke for it,which I have with this transmission.The shaft on the 375 is of the size of the 400.so all you need is the 400 shaft cover and the 400 yoke and its all good.Bruno.