I am looking for a input shaft , can a use rx7 turbo2 input shaft on b2600

Hello, this is a completely different unit. You cannot interchange those parts. However, if you want to try and maybe locate something possibly more plentiful -- check for a Ford Ranger or Ford Explorer of the same vintage. They utilize the same 5 speed Mazda transmission as your 1991 B2600. I'm not sure of the model year change over, but I am certain that there are common parts with the Ranger and Explorer...especially the 1991 Ranger.

In addition - make sure the “input shaft” is indeed all that the transmission needs .. Just trying to save you from having future transmission problems