It has a camper body on it so it’s carrying a bit of extra weight (so is its driver lol) it has a 1.6 transfer box will I lose much acceleration with a 1.2?
The 1.6 is very short gearing and a Tdi doesn't rev very much.
I'd need to check for certain, but I'm reasonably sure a factory 130 with a Tdi would have had a 1.4 transfer box, but this would have been the tall gear-set LT-77 with the 200Tdi or the same gearing with an R380 and a 300Tdi.
I'm guessing your LT-77 hails from a 19j 2.5TD or even a NaD 2.5? Which means you'll have shorter gears. The 1.2 transfer box from a Disco 1 will give very similar gearing to the factory setups. If your LT-77 is the Tdi gearset, then a 1.4 would suit better.
As for acceleration, yes and no..... the 1.6 transfer box and short gearing must mean you can pull 5th gear from just over 20mph. But you are probably topping out around 50mph and maybe screaming its head off to get to 60mph.
Taller gearing will give a better spread of speed and allow a wider speed range in each gear. So you'll need less gearshift to attain most legal speeds. This might mean you can get down the road better with the taller gearing.
My brother has a 90 that we put a Tdi in, it had the short LT-77 and 1.4 transfer box. Recently swapped to the 1.2 and it has transformed the vehicle. The 90 isn't a camper, but it carries plenty of tools and weight and often tows. The 1.2 has been no detriment.
Ashcroft Transmission have a gear calculator on their site if you want to have a play around with the different options.
