Help identifying my transmission

[Peanut74]

This one has me stumped big time.
The transmission that came in my '67 appears to be a TH350. HOWEVER, it has only two speeds. The trans pan has the angled corner notch and 13 bolts indicating that it's a TH350 which is a three speed. Thought maybe it a TH250 but that's also a three speed from what I found. I may at a loss as to what it is. Any help in identifying it would be greatly appreciated.

[Stocker]

Defective TH350 that fails to engage one of its three gear ratios?

Is there a transmission listed on the SPID?

[Ol Blue K20]

Powerglide- 2 speed auto

[Getter-Done]

Here's a link with info.

Sounds like there issue with the transmission not shifting.

Link: https://www.chevyhardcore.com/tech-s...uminum%20units

[Peanut74]

I went under the truck and shifted it manual and it is indeed a two speed. I went back underneath it looking for any markings on the transmission case. The only thing I found was 8T. There was no M33, M38 or M39 on it. Snapped a couple pictures hoping that would help.

Also, the guy I bought the truck from just had the transmission rebuilt.

[Stocker]

I was not aware that a Powerglide was still used in some of these trucks. Does a Powerglide have the angled corner on the pan? Seems like I learn a bit more almost every day -- or learn how much I don't know.

Peanut, if you can talk with the shop that rebuilt the trans, they should be able to fill you in on all the details.

[Getter-Done]

Maybe the guy that rebuilt it done a custom job.?

How long is that tailshaft?

That appears to be the T350 case.

There was a long and short tail shaft on the T350.
There was also a 12" tail shaft on some T350 cars.

The aluminum case powerglide had 14 bolts in the pan.

The Early Powerglide was Cast iron and IIRC it did not have a pan.

[SRU1436]

Look at the pans, they are different.

[Steeveedee]

Sure looks like a 350 pan. How many notches in the detents of the shift selector? Six (PRND2L) would mean a three forward speeds (THM) and five (PRNDL) would mean two forward speeds (PG).

In the two gears, how fast do you go at what RPM?

As an afterthought, does it shift on time? If the vacuum modulator is weak it can shift way late or not at all, and you might not be getting high gear.

[Peanut74]

The tail shaft is 9"-9.5" which falls in line with a TH350. I have disconnected the shift linkage and have five stops (P, R, N, D, L). The truck last time I drove around the house never shifted into drive. It just stayed in low.

[hugger6933]

All the Glides I used to have [drag racing application] had fins on the case [or ribs maybe] the went from the sides across the top. this does not look like any power glide I ever saw. Jim

[geezer#99]

Turbo 350 had the vacuum modulator on the passenger side at the back like in the pic.
Powerglide had the modulator on the drivers side at the back.
You got a t-350

[Rust_never_sleeps]

I've heard of dirt track racers building 2 speed TH350's, but that seems really far-fetched for a truck tranny

[Peanut74]

Well I crawled under the truck with phone in hand and confirmed it is indeed a TH350 like everyone thought. That only leaves the question of why do I have only 2 speeds instead of 3.

[Stocker]

That's progress. Have you been able to determine which two gears you have, and which gear is missing?

[Getter-Done]

This is what makes me think it is Customized.

The arrows pointing to the Tailstock / Silicone.

And the electrical Plug. ?

[Peanut74]

Getter-Done the electrical connection is for the digital speedometer. The transmission was rebuilt just before I bought it. So that would explain the silicon on the tailshaft.
If anyone has a TH350 laying around could you manually shift it and tell me how many stops it has.

[RustyPile]

Originally Posted by Peanut74

Getter-Done the electrical connection is for the digital speedometer. The transmission was rebuilt just before I bought it. So that would explain the silicon on the tailshaft.
If anyone has a TH350 laying around could you manually shift it and tell me how many stops it has.

Let's get the nomenclature correct, it's "detents", not "stops".. Including PARK, mine has six...

[WorkinLonghorn]

In post #10 you said "The truck last time I drove around the house never shifted into drive. It just stayed in low."

I think you need to get it out on the road to do a proper test drive. If it still won't shift out of low, I would check the governor. They get stuck. I've seen it happen a lot. Very easy fix but don't take it to AAMCO , just do it yourself in a few minutes. -BA

[Ol Blue K20]

Originally Posted by workinlonghorn

in post #10 you said "the truck last time i drove around the house never shifted into drive. It just stayed in low."

i think you need to get it out on the road to do a proper test drive. If it still won't shift out of low, i would check the governor. They get stuck. I've seen it happen a lot. Very easy fix but don't take it to aamco , just do it yourself in a few minutes. -ba

x2....

[leddzepp]

Originally Posted by ol blue k20

x2....

x3

[Lokin4AReason]

looks like a turbo 350 w a long tail shaft

only other way to make sure , is to count bolt(s) on the trans pan and the shape of it

[Peanut74]

Son inlaw got a K5 Blazer with a TH350. He sent me a picture of the column shifter indicator and it matches what I have. So tomorrow I will go over and see how many stops/detents his has. I will probably make a pattern of all the shift locations to compare to mine.

[Steeveedee]

As mentioned above there are six notches for a 3 forward speeds transmission.

Park
Reverse
Neutral
Drive
Second
First

[PbFut]

Only 5 detent positions seems odd. You are counting with linkage disconnected. Assuming you have six, have you verified vacuum at the modulator? A damaged or disconnected vac line will disable 3rd gear shift on my truck. Also a poorly set kickdown cable could be locking out 3rd. If you only have 5 shift positions you have something amiss internally.