well i could guess...but really you would need to find out yourself, too mant variables-
if you have a 4cyl non sport or TRD then you probably have a 8 inch
i believe most TRD lockers and lsds are 8.4 inch
hard to say, they even differ between auto and manual trans
what i suggest is taking a few pics and posting them, as well as getting all the numbers off of the axle id tag, front and rear, and contacting marlin or other marlin employees that have experiance with these axles
alot of people here, including myself, could probably tell you what you have if you posted pics though
