will it fit b4 he buys it

my mates 1994 300 tdi 90 has gearbox issues.hes been offerd a td5 r380 gearbox and transfer box.but will it fit the 300 and are the trasfer box the same ratio or different.he doesnt want to part with the wonga untill he knows for sure,so im asking the font of knowledege any help please?

I think Ashcrofts have a definitive guide as to what is what.

the gearbox wont fit as the input shaft of the td5 box is something like 285mm and the 300 box will be about 180mm long. Transfer box from a disco should be the same but may not have diff lock.
Find a 300 box.

many thanks thats saved him a 5hr round trip