2.5TD to tdi - why swap transfer box?

Hi,

Having read several threads on both 200tdi and 300tdi conversions to try and work out which engine would be easier to do for someone who can't weld (200tdi is winning at the moment).

I see some of the 300tdi conversions say to change the transfer box for the Disco one. Why is this, what diference does it make?

(I'll be keeping my LT77 gearbox)

higher ratio - gives a higher top speed or better cruising.

Thanks,

So, I'd guess that would mean a trade off for some of the bottom end power?

Never did fully understand gearing.

low box would remain unchanged if you do loads of road miles thats when pepes generally do the transfer box,

If you're keeping the LT77 then you're probably better off with a 200 if you can't weld, as the connections are different for the 300 and the R380 box. 200 out of a disco is way cheaper and slightly more powerful but you will need to buy (again if you can't weld) some conversion downpipes and it's a bit more of a faff.