My 1030 parts book shows the radiator p/n to be
3 438 839 M91 (radiator assembly)
The 1020 radiator would be the same.
I suggest as someone else, that your best best is to have the old one repaired. They can take off the tanks and solder on new tube/fins. A new radiator would probably cost 5x the cost of a repair.
Hope this helps.