Transfer box ratios

Hello, I have a 1986 90" with a freshly machine-shop refurbished 200tdi mated to a decent LT77. I will not be off-roading or towing 3 ton loads but want better road speed. Should I fit a Disco1 transfer box?

Tbh the 1.4 is pretty good at what it does in the 90/110 models, I found the 1.2 was to highly geared and the box effectively became a 4 speed as 5th was unusable a lot of the time, it was okay on fast a roads and motorways, but then it lacked grunt on long inclines, this was all solo running empty.
So in my humble opinion if them tyres in your pic are 235/85 then stick with the 1.4.
A lot depends on the terrain around you and your regular haunts.

Ashcrofts do a 1.3 ratio change gearset now too which I think is supposed to be a very happy medium. Obviously needs some mechanical knowhow to fit.

Hello and welcome to LZ

I've had 1.2s with 33x12.5s on one of my 110s and it was perfect and that was with alot of towing too.
Fact it was a 200bhp/450Nm TD5 helped however

I have a 110, 200tdi with the disco box, on 235/80s.
I tow and move up to 1 ton of boat and trailer, up to 25 miles in Norfolk no problem.
I drive up to 200 miles in a single trip, not towing, half "A " road, half A1/A1M, I find the disco box much better, quieter, for comparatively high speed 60-70mph driving. I don't mind dropping to 4th occasionally it's not that. different to being in the old 5th.

Welcome to the forum