hey guys have done the intake gasket , and wanted to replace the cat with one of the highflo., found this link says bolts right up.
Magnaflow 23285-Magnaflow Catalytic Direct Fit-Chrysler Dodge Truck-Hottexhaust

But looking under my truck mine dont look like that ,
mine is one line in one line out, my cat looks more like a glass pack or cherry bomb (cylindrical) ,, I have a 2000 ram quad . 4x4 with the magnum v8

maybe it dont need replaced.. ?

 

is there a Y before the single in, in otherwards how do the two header pipes connect into that one? I have this cat and thats how my stock was set up but i think 2000 OR 2001 have a y pipe before the cat

 

yeah mine has a Y yoke,, into a single ,,
pipe looks pretty rusty on outside, but may be fine inside . no leaks/. 116000k on her