How to know if it's a Jack built transmission

[Oldsid]

I need a transmission and someone has a used one for sale and claims it's a Jack transmission. The owner said that he has the built list but I am not sure if it's an actual invoice. I am going to check it this weekend and would like to know how can we tell if this transmission was really a Jack's built and what kind of details/test? can we do to inspect the transmission.
Thanks

 

[keltalon]

Most reputable builders will stamp some type of identification on the case to let themselves know later that is is one of their units. I personally have not ever seen one of jacks units but I do have a tre unit and not only is the case stamped tre , john puts tre on every gear and everything else that he touches inside and its gonna have tre engraved on it. On the bell housing tre puts an id number, so that when you call him you can give this number for quick reference for him to look up the work order. With jack being as detailed as he is I can imagine that he will have something similar. If it's a true a jacks unit buy that sucker he does good work!!

 

[1990TSIAWDTALON]

I have a Jacks unit, I will look at the ID pad and see if there is anything on it that is not normal. If I can, I will take a picture of it and post it up for all to see. It's been over a year so I can't remember off the top of my head.
Here is what the "documentation" should look like though, it's my invoice:

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[mitsumike0]

One time I was trying to buy a jacks Trans off someone who had no paper work. I ended up giving the person at jacks the name of the buyer and the state he/she lived in. With that information I was able to get an invoice.

 

[Oldsid]

Thanks for the help guys.
The owner of the transmission is not the one who had done the built so I am not sure if he has any document that can prove what he is claiming. I may be able to see it this Sunday and I will check if there is any engraving or stamping.
Besides that, what kind of signs should I be looking for to check that transmission is in good working conditions?