How difficult is it to rebuild a 091 gearbox.

Very difficult for me. I got a workshop with the required presses and experience to do the job

Fairly easy reading the workshop manual.......but its the jigs & experience to know what you're looking for that makes it work.......

I enjoy the 091's better than the swingaxles......

Opinions can vary greatly. Yeah?

I am going to try it but need a jig and a good book. I also think albins should make 4.0 ring and pinion for these.

They will make what ever you want if you can wait, and have a good budget.

You can 'get by' with home-made jigs and tools,
but an experienced eye is an advantage.
Take your time and look closely at the details.

good luck and good on you for having a go.

Dangerous i was thinking that maybe you wanted to help me in this project but first i want to get the rebuild video from long enterprise in the USA.