This is the story. I just pulled a transmission from a 1986 van. The engine was a V6, externally balanced flex plate, with center bolt valve covers and the transmission looks to be a TH400. The trans pan looks like a 400. It has a vaccum modulator and a one spade plug-in on the side. It has a 6 bolt hex pattern for the tailhousing. But here's where I get confused, the tailhousing is 9" long, overall length is just under 35" , the slip yoke is a slip on with 27 splines. It isn't stamped TH375 on the underside of the tailhousing either. I can't find any id numbers on it. The pan has Turbohydramatic, Division of GM stamped on the bottom. The bellhousing has HD 42 on it and that's it. Help would be appreciated.