the fans are held in with 3 nuts/bolts and you simply undo the 2 securing bolts for the fan shroud, unplug the loom to the fans and pull it out

you can then mess about with it on the bench as the fans will more than likely have these threaded bits corroded

if the fan is siezed you can simply replace them and slot them back in again, almost the easiest thing to do on a sierra

apparently the diseasal fans used a slimmer shroud so you could always try and find them

alternativly you can also mount the rad in one of the more forward mounting holes in the chassis legs to give you more clearance if you feel the standard twinky fans aren't up to scratch room wise

the sierra's were biult to such a random standardization that what may fit on one won't fit on another car, even though the shells are identical