I have 2 transmissions. A 1986 TH-700R4 and a 1988 TH-700R4. What is the difference between them? I heard somewhere that in 1988 they made em stronger, and I an under the impression the a 1988 is a 30 spline and a 1986 is a 27 spline. How can I tell? Which one is the best to use? Any comments would be appreciated.

 

Actually they both should be 30 spline on v8's.

The differences range from more vanes in the pump and other pump mods to larger sprags, hardened planetaries, a better valve body.....

If you have a choice go with the 88. If the 88 trans is shot put the 86 in for now and do/have done a good performance rebuild on the 88 if your're planning on putting serious power through it.

As for bolt up differences, they are alike.

If you need to determine a good trans from a older (weaker) trans, pop the pan and look at the valvebody. There should be a metal tube running from the pump to the rear of the case (into an aux valvebody, made of aluminum) The older trans had a 'blockoff' plate installed at the back. That's prolly the easiest way to tell, but a later tranny thats shot isn't better than a earlier model in good condition.

Hope this answers your ?'s