series motors with different radiators

when buying radiator fora turbo2 fc they sell like a 87 and 88 then a 89-like 91 i think why though? my car is a S4 the motor im putting in is a S5 how do i knwo which aftermarket radiator to use ? i mean why are they different with series are the mounts different or something?

not sure, but just get a koyo rad.

yea they are koyo they stop from 88 then start back at 89 so i dunno i dont see wehre either one of them would be different beside maybe hoses

i think the filler neck location is different
its that or the mounting is different

get it to match your engine year