727 Small Block Torqueflite Convertor

you can tell the difference between a lock up and non lock up by this.

if it is a lock up transmission the splines on the input shaft will not go all the way down the shaft....the end of the shaft will have like 1" area of machined smooth shaft showing.

a non lock up transmission the splines will go all the way down the shaft.

I am not a 727 expert so i can't say how many splines you will have.

let me do some research for you real quick and I will tell you what I find!