The 4-speed manual trans cars had a factory modified floor pan to accommodate the trans, like an afterthought! The “hump” to accommodate the 4-speed trans and floor shiftier was spot welded to the floor pan, after the original floor pan “hump”, made to fit a 3-speed or automatic trans, was cut out. A real Rub Goldberg modification! The floor pan in the car you recently bought should show this 4-speed modification.
Pic of my 4-speed floor pan attached.