Are there different springs for the TV system depending on what car the transmission is in?

Here's my thought. I traded in my core from my '91 truck for a rebuilt 700R4 that ended up being out of an '89 something. After 1200 miles, the transmission is garbage. The TV cable was adjusted properly, but it still slipped (slips) from a dead stop. It seems like there just isn't enough pressure to keep it from slipping. I bought the corrector spring that everyone is talking about, and that seems to help, but I won't know for sure until the transmission is rebuilt...again.

So I'm wondering if there is something I'm missing here or something that I need to tell the rebuilder to keep this from happening again?