Even all lol

My mrs has a pd100 golf and I have a pd 100 fabia (estate)

The gears in my mrs golf are far shorter than my furby gears, say @ 60mph my furby sits @ 1800rpm and my mrs golf at 60mph sits a 2000rpm and tops at around 125mph where as my furby I've seen 130mph and was no where near all out, all on a private runway of course :p

Will a 5speed box from a mk4 golf fit in my furby or is there to much to change?

So you are wanting to fit the golf box to yours to give you shorter gears?

 

It could be that the gearboxes actually have the same ratios but due to diff and tyre sizes the overall gearing to the road is shorter?

 

You would ideally need to get the engine and gearbox codes to see if they are compatible.

 

Phil

+1, this calculator might help once you've got all the information:

http://www.myturbodiesel.com/1000q/tire-wheel-gearing-calculator.htm