Hi I just bought 1977 series 3 with early defender 2.5 diesel engine and need to fit p.a.s the vehicle has range rover diffs with 16 inch wheels and wide tyres so you can imagine how heavy it is to steer.

Is there a ready made kit to fit?

WELCOME! I guess

I believe there is...
The Bullworker Official Site | Bow Products

After such a sketchy introduction, you may want to have a look in the Series section and post your question in there. I'm sure there's knowledgeable tratterers who will help.