At 85k I wouldn't change my a AT fluid unless it was dark and smells burnt, a shame they stopped putting a dipstick on later cars! The rubber hoses to the radiator can be difficult to remove from the transmission metal pipes but once you've got them off they go back easily. I only replaced mine because one was split but if they look ok they should be alright, unless you replace them for peace of mind. OEM is the way to go for a radiator if you can afford it, there are plenty of non OEM ones but many won't fit a UK car without adaptions which isn't ideal. You'll also need 5 litres of Toyota ready mixed red coolant. The foam in-between the radiator and AC condenser will fall apart but I've always just left it off. This is how confusing aftermarket can be, both LS430 radiators but slightly different, the top one with the nozzle on the top far right will fit properly but the bottom one won't because it doesn't have it so would need adapting. And some now don't have radiator caps.