250 transmission on 305 engine in 76 nova interchangeable w/ what

[hardhatdrummer]

i got a 250 transmission in a 76 nova on a 305 engine what is this transmission interchangeable with? i wanted to get a cheap rebuilt 250 transmission off ebay but they dont have any they only have 350s can i use a 350 and are there diff kinds of 350s that will and wont fit? please help

[bobss396]

A '76 Nova should already have a TH350 in it. Try to find out exactly what you have first, there are transmission identification sites that will show you the outline of the tranny oil pan. Any Chevy transmission will bolt up to the 305, the lengths are also the same, somewhere close to 29.5" from the bellhousing to end of the output housing. The only longer one I'm aware of was the TH400 used in older Chevy wagons.

Bob

[silicon212]

Originally Posted by hardhatdrummer

i got a 250 transmission in a 76 nova on a 305 engine what is this transmission interchangeable with? i wanted to get a cheap rebuilt 250 transmission off ebay but they dont have any they only have 350s can i use a 350 and are there diff kinds of 350s that will and wont fit? please help

The TH250 is outwardly nearly identical to the TH350, except it has an external band adjustment on the passenger side above the 1-2 accumulator. In fact, this is the identifying feature of the 1976 TH250 (later TH250s have a ribbed, deep pan that the TH350s don't have, in addition to the band adjustment). The TH250 is a light-duty transmission based on the TH350. Where a TH250 is, a TH350 will bolt in fine, and is preferred.

As to the 305, it is a Chevrolet small block and as such, any transmission designed to bolt to a Chevy V8 will fit it.

[randy78]

these will interchange:

200r4
th350 with 6" tail
thm200
thm250

plus a few others but very uncommon


not all the 73-up novas had th350, it is a common misconception/assumption that they all do

the easy way to ID a 250 is by looking at the pan for a huge indented X in the pan


if no big x and it is is 13 pan then its a th350
if its 11 bolt and identical in shape to a th350 and 250 then its a 200


if you go with a 200r4 then take note of this:

Transmissions marked "**" have a special (better for performance) valve body, plate, 1-2 servo, 3-4 servo, 2-3 intermediate servo, and governor.


http://www.442.com/oldsfaq/oftrn.htm



good luck

[silicon212]

Old thread.

The "X" identifying feature on the TH250 is valid only for transmissions from 1980-onward. Earlier versions, as I stated above, have no other outwardly identifying features aside from the band adjustment. The <1980 TH250 has the exact same pan as the TH350.

1974/75 Novas got the TH250 *IF* the engine was the 4.3 liter (262) small block, or the straight 6 250. 305/350 powered models from 1976 onward generally got the TH350, though some 305 powered units got TH200s. It is common that these have been replaced at some point with a TH350.

TH200/C pan is SIMILAR in shape to the 250/350/375B however it is different. The main identifying feature of a 200/C is the word "METRIC" on the pan, and a lack of vacuum modulator. TH250/350/375B have a vacuum modulator at the back of the transmission on the passenger side, above the pan "cutout", and do not contain the word "METRIC". Early TH350s, up to about 1973, also have a factory drain plug in the pan. TH250/350/375B have 13 bolts holding the pan, TH200/C has 11.

The TH2004R has the mount in the TH400 position - important if the car doesn't have provisions for this!



1. Powerglide
2. TH200/C
3. TH250/C/350/C/375B
4. TH375/400/3L80
5. TH2004R
6. TH700R4/4L60/E
7. 4L80E

A TH375 is a lighter-duty TH400 with a TH350 output spline size. Used mainly in Oldsmobile B-cars of the 1970s. Output shaft housings on these are marked "TH375" under the mount mating surface. A TH375B is a heavy-duty TH350.

[Blue Bowtie]

Umm... Which Powerglide? Aluminum, iron, or air-cooled?

[silicon212]

Aluminum, sorry.

[ekg125]

I just swapped out a THM200 with a TH350 in my 1976 Nova, and the only things we had to do was rob the 200 of the shift linkage bracket, and run a vacuum modulator hose to a 'T' into another vacuum line.