Longer 5th gear

[Ä‘uro]

Cheers guys

As my gearbox is originaly fm Seat Arosa , this means on 60 mph rpm are around 3500. This is apsolutly non workable for long distance traveling or highway. For sure good ratio for hill climbing

I would like to keep first 4 gears as it presently is but would like to hv 5th gear with much longer ratio.
Could somebody advice fm which gearbox I could use transmition to extend 5th gear (e.g. 60 mph/ 2800 rpm or similar)

Also some VAG barcode would be helpfull to trace more quickly

Tks
Damjan