1988 would be 30 spline input shaft

 

I would try to find a way (without the obvious pulling of the trans) to verify your trans is an 88 build. Since 88 is the first year for the 30spl; its theoretically possible you might have an 87 trans in an 88 truck.

 

The input shaft splines were changed from 27 to 30 splines in 1984 model yrs as I recall

 

IF the first character in the stamping on the pan flange is an 8, then it's an '88. If it's an 88, then it's 30 spline.

But I have another question. Why do you think you are having a torque converter issue and not a 3/4 clutch failure? Or any other dozens of possible/potential problems with your transmission?

 

Torque converter has a small rattle during regular acceleration. I checked the flex plate bolts and they are tight, no visible cracks in the flex plate. Trans shifts fine, fluid looks fine, no burnt smell. My conclusion is that the converter is having an issue. .

 

Like '49 said, a number of things could be the culprit to your rattling noise. I recently started driving an '88, like yours, as a daily driver. One of the first things I noticed was the heat shield on the catalytic converter rattling.

 

How are you narrowing it down to the torque converter ? Could it be the front universal joint? Tailshaft bushing? Driveshaft angles off? Just thinking out loud......

 

My 1988 Chevy does not have a catalytic converter on it. I removed it. I also converted it from TBI to carb and stand alone HEI ignition. The noise is definitely coming from the front trans/ bellhousing area. At first I thought it was a detonation noise but alas it is from the front of the trans. The transmission shifts fine and the noise is only under light to medium acceleration and goes away after at 2000 RPM. No noise under hard accel. No noise under cruise or highway speed. I really don't want to wait until it totally fails and causes other trans damage. I have 2 four post lifts but they are both outside and we have about 6 inches of snow right now. so, come springtime I will change out the converter. I do appreciate the advice.