I have been searching the transmission posts lately and have seen some information concerning changes to the 700's over the years. Recently I did some work on my tranny and noticed that it has an auxiliary valve body that would make it an 87 or newer transmission. I also noticed the wiring on the valve body to be slightly different that what my GM manual shows for an 85 f body with a 4 barrel. So would these differences effect the operation ,or lets say would this transmission be compatible with my 85 electronics. Since I got the car it seems to be in a hurry to lock up the convertor. The 85 should have 3-4 switch that unlocks the convertor when there is a down shift and this one appears to have a temperature sensor in it's place.

 

It should be fine.

 

On may 10, 1988 the 4-3 pulse switch was eliminated. Post the code on the pass side of the case, just above the pan gasket, and I will break down the origional application for the trans you have.

 

I'll get back under there and scrape the grime off and see what it says . Thanks

 

Floor Guy here are those numbers 9YPM223 and the last digit is 8 or B. Thank you.

 

That trans came out of a 1989 model, 5.0 liter f-body. The wiring you described earlier is what belongs in that trans. a 4th gear switch, a temp switch and a solenoid.
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I hate the lock up in third gear. It annoys me. On my cars I run a 4th gear only lock up kit. Makes the car more pleasant to drive.

 

Thanks Floor Guy , I have a switch installed in the brake switch wiring and I lock the convertor on the highway because mine locks in second and it is less than enjoyable. I see some of the performance chips say they delay lockup do you have any knowledge of the extent of the change they make?

 

The chips change the mph that the lock up occurs. I still run the stock programming in my car and chose to run the 4th gear lock up kit instead. Either way, you can alter it somewhat to suit your needs.

 

Should I make the wiring as it was in 85 with the 3-4 pulse switch instead of the temperature sensor?

 

You could do that. You may want to keep the temp sensor and splice it in though. If the trans runs hot, the switch trips and forces lock up to occur, resulting in lower temps. It is a good safety feature to have.

 

Thank you for your time and the use of your knowledge.