Got me a transmission, will it fit?

[tomboy mechanic]

went down to the junkyard and had a transmission pulled. only thing is, they pulled it out of an 87 truck (old body), but they told me and my dad it will bolt directly behind my 1990 truck with the same engine. my truck is a 1990 chevy 1/2 ton 2wd auto with a 5.7l 350 v8. the transmission i got is also an auto, and that was pulled from the truck that had a 350 in it. my question is, will this transmission bolt directly to my engine, or is this a different design?

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[Big D]

What transmissions did you pull...

 

[someotherguy]

Sounds like 700R4/4L60, main possible difference between the two will be the '87 -might- have a cable-drive speedometer. Fail. Very easy to see just compare the tailshaft housings between the two transmissions.

Richard

 

[tomboy mechanic]

yea, on my truck there is a cable coming from the rear of the transmission tail housing, so then i assume this is the speedometer cable? i'm not too sure, as i have worked on my dad's 98. his is a 5 speed with an electronic speedometer, so i'm not too familiar with the automatics, as of yet.

 

[someotherguy]

Let's try to keep the different trucks clear and be specific.

You have a 1990 C1500 5.7 automatic. This truck uses the 700R4/4L60 (note: not 4L60E) transmission, which has a throttle valve cable (TV cable) that hooks up to the throttle body. The speed sensor is electronic; that is on the tailshaft housing and has a two wire connector to it.

The boneyard truck is a 1987 (squarebody) 5.7 automatic assumed C10 (2WD half ton). This also uses the 700R4/4L60, will have the same cable that attaches to the throttle body, but will almost surely be a cable drive speedometer.

Will it bolt up to your engine? Absolutely. But you won't be able to plug in your speed sensor connector. The tailshaft is missing the reluctor wheel necessary to make the speed sensor read. You could install the reluctor wheel onto the shaft though it's a bit of work.

Also considering it's a boneyard transmission you should be sure it's even a 700R4, could have been swapped for something else (often a TH350 3-speed non-overdrive) in the past. The two transmissions you have now should look practically identical other than the speed sensor/speedometer cable drive.

Richard

 

[tomboy mechanic]

thanks, now that clears it. maybe when i have the transmission out of my truck i'll have a closer look at it. i couldn't tell because it was dark under there. i didn't know the names of each transmissions, except engines.

well, thanks again.