Small block mini starter

Ok The original starter on my 273 had a run on due to a worn out friction washer.
I thought I would go ahead and install a mini starter. Got one from a 93 dDakota at the parts yard. Dropped my original starter. Went under the car with the mini starter and found the original bolts dont work. I stuck a new friction washer in my original stater and put it back in service.
It's been so long that I can't recall exactly what was different. I did pick up the 2 bolts I needed later on at Lowes but right now I can't recall what size those are more than 7/16 X something.
It could be that my original starter is mounted with one bolt and one stud with nut where the mini starter has 2 threaded holes requiring two bolts.
Anyway... It might be a simple bolt on for most but not all. Have fun