Trans Numbers

[dq409]

Today i was moving some stuff out of storage and have this trans with a casting number of GM 6 - 3858486 that can be a 3 sp or 4sp.
How do you tell if it is a 3 or 4 Sp?
I think the numbers come up as a Saginaw but am trying to figure out wht it is.
I also have two bell housings that are numbers 3788421 and 3840383.
Both are alum. What are they?dq

 

[Tom Kochtanek]

421 housing

DQ:

This is from memory, but I think the 421 aluminum bell housing was used on the SBC. I have one on my 1963 Corvette 327 four speed.

Not sure about the other stuff!

Cheers,
TomK

 

[tripower]

3840383 is for 153 tooth flywheel. They were OEM on 69 Z28's. The 3788421 was a small hole bellhousing and it was the small brg retainer hole, it was specific to 1963 Corvettes with the T10 or later 63 issue small aluminum front brg retainer Muncie.

 

[Ronnie Russell]

Dan is correct about the #421 bellhousing , but I would add it was also 63 Passenger car with 327. I had one and I think impalaguru also has or had one in an Impala.

 

[oldskydog]

Today i was moving some stuff out of storage and have this trans with a casting number of GM 6 - 3858486 that can be a 3 sp or 4sp.
How do you tell if it is a 3 or 4 Sp?
I think the numbers come up as a Saginaw but am trying to figure out wht it is.
I also have two bell housings that are numbers 3788421 and 3840383.
Both are alum. What are they?dq

Count the number of shift levers on the side. The saginaw 4 spd has the reverse lever on the side cover instead of the tailshaft housing. 3858986 shows as the maincase for a 3 spd Saginaw with 2:54 1st gear in 66-67.

Here's an interesting article on converting a Saginaw 4 spd to an overdrive by bolting the overdrive unit from a 65 up 3spd OD to the saginaw 4 spd main box.

http://www.chevytrucks.org/tech/overdrive.htm
:

 

[dq409]

Count the number of shift levers on the side. The saginaw 4 spd has the reverse lever on the side cover instead of the tailshaft housing. 3858986 shows as the maincase for a 3 spd Saginaw with 2:54 1st gear in 66-67.

Here's an interesting article on converting a Saginaw 4 spd to an overdrive by bolting the overdrive unit from a 65 up 3spd OD to the saginaw 4 spd main box.

http://www.chevytrucks.org/tech/overdrive.htm
:

OK, so it looks like it is a 4 spd, yes?
Numbers on the side cover is, GM4 3858992

I take it either way the Saginam is a low performance trans, yes?

 

[oldskydog]

OK, so it looks like it is a 4 spd, yes?
Numbers on the side cover is, GM4 3858992

I take it either way the Saginam is a low performance trans, yes?

3 speed...only two shift levers. Strong enough for anything under 350hp. It was used on 283's and 250, 275, 300 hp 327's. Anything bigger got a Muncie.

 

[W Head]

Saginaw

DQ, All three speed Saginaw Trans, 1st gear 2.54-2nd gear 1.88 and 3rd 1.00, so says my GM Trans. chart. All 4 speed Sawinaw 2.20-1st, 1.64-2nd, 1.47-3rd and 1.00-4th.

W Head

59 El Camino 348-3,2s
59 Impala 409-2,4s

 

[dq409]

3 speed...only two shift levers. .

DOH !!!!!