Well, it seems I may have to rebuild the T56 already, and I'm just wondering what parts are a must as far as upgrades when I do pull it apart. Steel 3-4 fork, and billet keys I know, but is there anything else like that which will boost the longevity without totally emptying my pocket?

 

Mainshaft upgrades are hundreds$.

On a trans. with miles, you need to take it apart to verify what parts it needs anyway.