I cross referenced two sources for 73 & 70 disk brake seals... and there is a difference.
If you have OE 70 spindles & disks # 5121S
If you have later model spindle & disk # 5121 (same #, no S)
These numbers are used for several brands including National & Timken, You might see if your local shops can get wheel bearing seals with these numbers.
http://www.rockauto.com I think will ship overseas