93 Nissan Maxima Transmission

I am looking for a reliable replacement or fix for my 93 Maxima transmission. The overdrive (aka “into neutral at 70mph”) is about gone. This is my second transmission. The stock transmission is not up to the gaff of the single overhead cam engine (not the SE). So, is there a beefed up replacement or other fix for the overdrive slipping problem? Thanks for your help.