5 spd trans

I would be surprised if you can find a 5-spd bell-housing for a slant six. Research 80's trucks, since that might be the best bet.
There are no factory 5 speed bells. But some of the stranger slant lovers (like me) do have bellhousings with T5 adaptor plates attached to them sitting on shelves. Maybe someone (not me) would part with one if you posted a wanted ad. Mine cost about $250 to have the adaptor and pilot bearing spacer made around 2005.